feat: 书库导入导出/图片变体/书籍搜索/小组件运行时等

新增：
- 书库导入导出（library_import/library_export）及测试
- 图片变体生成（image_variants）与响应式图片（responsiveImage）
- 书籍搜索（bookSearch）+ BookSearch/LibrarySearchGrid 组件
- 小组件运行时（widgetRuntime）与静态检查（widgetLint）
- 上传缓存中间件（upload_cache）与字体 CSS 提取脚本

其它：
- 后端 handlers/services 全量调整
- 前端页面、组件、库函数与配置更新

frontend/app/admin/library/LibraryAdmin.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useMemo, useRef, useState } from "react";
+import { useMemo, useRef, useState, type ChangeEvent } from "react";
 import {
   BookOpen,
   Download,
@@ -17,6 +17,7 @@ import {
   apiAdminCreateLibraryDoc,
   apiAdminDeleteLibraryDoc,
   apiAdminDeleteLibraryFile,
+  apiAdminImportLibraryZip,
   apiAdminListLibraryDocs,
   apiAdminPurgeLibraryDoc,
   apiAdminUpdateLibraryDoc,
@@ -25,17 +26,20 @@ import {
   apiUploadPostImage,
   type LibraryDoc,
   type LibraryFileItem,
+  type LibraryImportReport,
   type LibraryInput,
 } from "@/lib/api";
 import { formatDateTime, formatRelative } from "@/lib/format";
-import { libraryDocPath } from "@/lib/urlStyle";
+import { libraryDocPath, userPath } from "@/lib/urlStyle";
 import { useUrlStyle } from "@/components/SiteBrandProvider";
 import { toast } from "@/lib/toast";
 import ConfirmDialog from "@/components/ConfirmDialog";
+import Avatar from "@/components/Avatar";
 import MarkdownEditor from "@/components/MarkdownEditor";
 import { AdminEmpty, AdminField, AdminPageHeader, AdminStatusChip, AdminSwitch } from "@/components/admin";
 import LibrarySectionsPanel from "./LibrarySectionsPanel";
 import LibraryCoverPicker from "./LibraryCoverPicker";
+import { densitySrcSet, isOwnImage, pickVariantWidth, variantURL } from "@/lib/responsiveImage";
 
 // 与后端 libraryAllowedExts 保持一致；前端先拦一道，后端仍会校验
 const ALLOWED_EXTS = new Set([
@@ -59,9 +63,12 @@ function formatSize(n: number): string {
 
 interface DocForm {
   title: string;
+  author: string;
   slug: string;
   description: string;
   cover_url: string;
+  cover_width: number;
+  cover_height: number;
   published: boolean;
   sort_order: number;
   entries_auto: boolean;
@@ -69,9 +76,12 @@ interface DocForm {
 
 const EMPTY_FORM: DocForm = {
   title: "",
+  author: "",
   slug: "",
   description: "",
   cover_url: "",
+  cover_width: 0,
+  cover_height: 0,
   published: false,
   sort_order: 0,
   entries_auto: false,
@@ -80,9 +90,12 @@ const EMPTY_FORM: DocForm = {
 function formOfDoc(d: LibraryDoc): DocForm {
   return {
     title: d.title,
+    author: d.author ?? "",
     slug: d.slug,
     description: d.description ?? "",
     cover_url: d.cover_url ?? "",
+    cover_width: d.cover_width ?? 0,
+    cover_height: d.cover_height ?? 0,
     published: d.published,
     sort_order: d.sort_order,
     entries_auto: d.entries_auto ?? false,
@@ -145,6 +158,13 @@ export default function LibraryAdmin({
   const [fileDeleteTarget, setFileDeleteTarget] = useState<LibraryFileItem | null>(null);
   const [fileDeleteBusy, setFileDeleteBusy] = useState(false);
 
+  // 书库导入恢复（上传导出 ZIP）
+  const importInputRef = useRef<HTMLInputElement>(null);
+  const [importing, setImporting] = useState(false);
+  const [importReport, setImportReport] = useState<LibraryImportReport | null>(null);
+  // create 模式遇到 conflict 时保留 File，供确认后 overwrite 重传
+  const [importOverwrite, setImportOverwrite] = useState<{ file: File; count: number } | null>(null);
+
   // 条目删除（软删）与彻底删除
   const [docDeleteTarget, setDocDeleteTarget] = useState<LibraryDoc | null>(null);
   const [docDeleteBusy, setDocDeleteBusy] = useState(false);
@@ -170,6 +190,34 @@ export default function LibraryAdmin({
     }
   }
 
+  async function runImport(file: File, mode: "create" | "overwrite") {
+    setImporting(true);
+    setImportReport(null);
+    try {
+      const rep = await apiAdminImportLibraryZip(file, mode);
+      setImportReport(rep);
+      const okN = rep.imported.length;
+      const failN = rep.failed.length;
+      if (okN > 0) toast(`成功导入 ${okN} 本书${failN ? `，${failN} 本未导入` : ""}`, "ok");
+      else toast("没有书籍被导入，请查看失败明细", "error");
+      await reload();
+      if (mode === "create") {
+        const conflicts = rep.failed.filter((f) => f.reason === "conflict").length;
+        if (conflicts > 0) setImportOverwrite({ file, count: conflicts });
+      }
+    } catch (e) {
+      toast(e instanceof Error ? e.message : "导入失败");
+    } finally {
+      setImporting(false);
+    }
+  }
+
+  function onPickImportFile(e: ChangeEvent<HTMLInputElement>) {
+    const file = e.target.files?.[0];
+    e.target.value = ""; // 允许重选同一文件
+    if (file) void runImport(file, "create");
+  }
+
   function openNew() {
     setForm(EMPTY_FORM);
     setSnapshot(JSON.stringify(EMPTY_FORM));
@@ -221,8 +269,11 @@ export default function LibraryAdmin({
       const input: LibraryInput = {
         slug,
         title,
+        author: form.author.trim(),
         description: form.description,
         cover_url: form.cover_url.trim(),
+        cover_width: form.cover_width,
+        cover_height: form.cover_height,
         published: form.published,
         sort_order: form.sort_order,
         entries_auto: form.entries_auto,
@@ -250,9 +301,13 @@ export default function LibraryAdmin({
     if (!file) return;
     setCoverBusy(true);
     try {
-      const res = await apiUploadPostImage(file);
+      const res = await apiUploadPostImage(file, undefined, "library_cover");
       if (res.url) {
-        patchForm({ cover_url: res.url });
+        patchForm({
+          cover_url: res.url,
+          cover_width: res.attachment?.width ?? 0,
+          cover_height: res.attachment?.height ?? 0,
+        });
       } else {
         setFormError(res.error || "封面上传失败");
       }
@@ -267,8 +322,8 @@ export default function LibraryAdmin({
   async function pickCoverFromMedia(attachmentId: number) {
     setCoverBusy(true);
     try {
-      const url = await apiLibraryCoverFromMedia(attachmentId);
-      patchForm({ cover_url: url });
+      const { url, width, height } = await apiLibraryCoverFromMedia(attachmentId);
+      patchForm({ cover_url: url, cover_width: width, cover_height: height });
     } catch (e) {
       setFormError(e instanceof Error ? e.message : "选用图库图片失败");
     } finally {
@@ -374,17 +429,103 @@ export default function LibraryAdmin({
         title="书库管理"
         description="书籍、文档与页面作品。书籍由介绍、目录与章节正文组成，像书一样阅读；附件仅提供下载分发。"
         actions={
-          <button
-            type="button"
-            className="btn btn-primary"
-            onClick={() => guardNav(openNew)}
-            disabled={saving}
-          >
-            <Plus size={15} /> 新建条目
-          </button>
+          <>
+            <a
+              href="/api/admin/library/export"
+              className="btn btn-ghost"
+              title="把全部书籍打包为 ZIP（介绍、章节、附件与封面），用于迁移或备份"
+            >
+              <Download size={15} aria-hidden />
+              导出全部
+            </a>
+            <button
+              type="button"
+              className="btn btn-ghost"
+              onClick={() => importInputRef.current?.click()}
+              disabled={importing}
+              title="上传导出的 ZIP 备份包，恢复书籍（介绍、章节、附件与封面）"
+            >
+              {importing ? (
+                <Loader2 size={15} className="animate-spin" aria-hidden />
+              ) : (
+                <Upload size={15} aria-hidden />
+              )}
+              {importing ? "导入中…" : "导入恢复"}
+            </button>
+            <input
+              ref={importInputRef}
+              type="file"
+              accept=".zip,application/zip"
+              className="hidden"
+              onChange={onPickImportFile}
+            />
+            <button
+              type="button"
+              className="btn btn-primary"
+              onClick={() => guardNav(openNew)}
+              disabled={saving}
+            >
+              <Plus size={15} /> 新建条目
+            </button>
+          </>
         }
       />
 
+      {importReport ? (
+        <div
+          className="panel mx-3.5 sm:mx-4 my-3 px-4 py-3 text-[13px]"
+          role="status"
+          style={{ borderColor: "var(--line)" }}
+        >
+          <div className="flex items-center gap-2">
+            <strong style={{ color: "var(--ink)" }}>
+              导入完成：成功 {importReport.imported.length} 本
+              （新建 {importReport.imported.filter((i) => i.action === "created").length} / 覆盖{" "}
+              {importReport.imported.filter((i) => i.action === "overwritten").length}），失败{" "}
+              {importReport.failed.length} 本
+            </strong>
+            <button
+              type="button"
+              className="ml-auto btn btn-ghost"
+              style={{ padding: "2px 6px" }}
+              onClick={() => setImportReport(null)}
+              aria-label="关闭导入结果"
+            >
+              <X size={14} aria-hidden />
+            </button>
+          </div>
+          {importReport.failed.length > 0 ? (
+            <ul className="mt-2 flex flex-col gap-1">
+              {importReport.failed.map((f, i) => (
+                <li key={`${f.slug}-${i}`} className="meta flex flex-wrap items-baseline gap-x-2">
+                  <span style={{ color: "var(--ink-2)" }}>
+                    {f.title || f.slug}
+                    {f.slug ? `（${f.slug}）` : ""}
+                  </span>
+                  <span
+                    style={{
+                      color:
+                        f.reason === "conflict" || f.reason === "deleted"
+                          ? "var(--warn, #b45309)"
+                          : "var(--danger, #b91c1c)",
+                    }}
+                  >
+                    {f.reason === "conflict"
+                      ? "同名书籍已存在，可覆盖导入"
+                      : f.reason === "deleted"
+                        ? "地址被已删除条目占用，需先彻底删除"
+                        : f.reason === "invalid"
+                          ? "备份数据不受支持"
+                          : "导入失败"}
+                  </span>
+                  <span>{f.error}</span>
+                </li>
+              ))}
+            </ul>
+          ) : null}
+        </div>
+      ) : null}
+
       <div
         className="admin-library-split"
         data-view={editorOpen ? "editor" : "list"}
@@ -435,9 +576,11 @@ export default function LibraryAdmin({
                         }}
                       >
                         {d.cover_url ? (
+                          // 36px 封面位：本站图走 48/96 变体
                           // eslint-disable-next-line @next/next/no-img-element
                           <img
-                            src={d.cover_url}
+                            src={isOwnImage(d.cover_url) ? variantURL(d.cover_url, pickVariantWidth(36)) : d.cover_url}
+                            srcSet={isOwnImage(d.cover_url) ? densitySrcSet(d.cover_url, 36) : undefined}
                             alt=""
                             className="w-9 h-9 rounded-lg object-cover shrink-0"
                             style={{ border: "1px solid var(--line)" }}
@@ -560,6 +703,16 @@ export default function LibraryAdmin({
                     ? `${editingDoc.sections?.length ?? 0} 章节 · ${editingDoc.files?.length ?? 0} 附件`
                     : ""}
                 </span>
+                {typeof editingId === "number" ? (
+                  <a
+                    href={`/api/admin/library/docs/${editingId}/export`}
+                    className="btn btn-line btn-sm shrink-0"
+                    title="导出本书为 ZIP（介绍、章节、附件与本地封面），用于迁移或备份"
+                  >
+                    <Download size={13} aria-hidden />
+                    导出备份
+                  </a>
+                ) : null}
               </div>
 
               {/* 书籍信息 tab（两个 tab 均保持挂载，避免章节编辑状态丢失）。
@@ -586,6 +739,15 @@ export default function LibraryAdmin({
                         className="admin-doc-title"
                       />
 
+                      <AdminField
+                        id="lib-author"
+                        label="作者"
+                        maxLength={100}
+                        value={form.author}
+                        onChange={(author) => patchForm({ author })}
+                        placeholder="作者或编著者，多位可用逗号分隔（可选）"
+                      />
+
                       <div className="admin-doc-field">
                         <label className="admin-doc-label" htmlFor="lib-slug">
                           访问地址
@@ -628,6 +790,7 @@ export default function LibraryAdmin({
                           placeholder="条目介绍，支持 Markdown…"
                           rows={12}
                           ariaLabel="条目介绍"
+                          uploadSource="library_content"
                         />
                       </div>
                     </div>
@@ -636,56 +799,58 @@ export default function LibraryAdmin({
                     <aside className="flex flex-col gap-4 lg:min-h-0">
                       <div className="admin-doc-field">
                         <p className="admin-doc-label">封面（可选）</p>
-                        <div className="flex items-center gap-2.5">
+                        <div className="flex flex-col gap-2">
                           {form.cover_url ? (
                             // eslint-disable-next-line @next/next/no-img-element
                             <img
-                              src={form.cover_url}
+                              src={isOwnImage(form.cover_url) ? variantURL(form.cover_url, 256) : form.cover_url}
                               alt="封面预览"
-                              className="w-12 h-12 rounded-lg object-cover shrink-0"
+                              className="w-full h-32 rounded-xl object-cover"
                               style={{ border: "1px solid var(--line)" }}
                             />
                           ) : (
                             <button
                               type="button"
-                              className="w-12 h-12 rounded-lg flex items-center justify-center shrink-0"
+                              className="w-full h-32 rounded-xl flex flex-col items-center justify-center gap-1.5"
                               style={{ border: "1px dashed var(--control-border)" }}
                               aria-label="上传封面"
                               onClick={() => coverInputRef.current?.click()}
                             >
-                              <ImagePlus size={16} style={{ color: "var(--ink-3)" }} aria-hidden />
+                              <ImagePlus size={20} style={{ color: "var(--ink-3)" }} aria-hidden />
+                              <span className="text-[11.5px]" style={{ color: "var(--ink-3)" }}>
+                                点击上传封面
+                              </span>
                             </button>
                           )}
-                          <div className="flex flex-col gap-1">
-                            <div className="flex gap-1.5">
-                              <button
-                                type="button"
-                                className="btn btn-line btn-sm flex-1"
-                                disabled={coverBusy}
-                                onClick={() => coverInputRef.current?.click()}
-                              >
-                                {coverBusy ? (
-                                  <Loader2 size={13} className="animate-spin" aria-hidden />
-                                ) : (
-                                  <ImagePlus size={13} aria-hidden />
-                                )}
-                                {form.cover_url ? "更换" : "上传"}
-                              </button>
-                              <button
-                                type="button"
-                                className="btn btn-line btn-sm flex-1"
-                                disabled={coverBusy}
-                                onClick={() => setCoverPickerOpen(true)}
-                              >
-                                <Images size={13} aria-hidden />
-                                图库
-                              </button>
-                            </div>
+                          <div className="flex items-center gap-1.5">
+                            <button
+                              type="button"
+                              className="btn btn-line btn-sm"
+                              disabled={coverBusy}
+                              onClick={() => coverInputRef.current?.click()}
+                            >
+                              {coverBusy ? (
+                                <Loader2 size={13} className="animate-spin" aria-hidden />
+                              ) : (
+                                <ImagePlus size={13} aria-hidden />
+                              )}
+                              {form.cover_url ? "更换" : "上传"}
+                            </button>
+                            <button
+                              type="button"
+                              className="btn btn-line btn-sm"
+                              disabled={coverBusy}
+                              onClick={() => setCoverPickerOpen(true)}
+                            >
+                              <Images size={13} aria-hidden />
+                              图库
+                            </button>
                             {form.cover_url ? (
                               <button
                                 type="button"
-                                className="admin-doc-textbtn"
-                                onClick={() => patchForm({ cover_url: "" })}
+                                className="admin-doc-textbtn ml-auto"
+                                style={{ minHeight: 0, minWidth: 0, padding: "1px 6px", fontSize: 12 }}
+                                onClick={() => patchForm({ cover_url: "", cover_width: 0, cover_height: 0 })}
                               >
                                 移除
                               </button>
@@ -749,6 +914,30 @@ export default function LibraryAdmin({
                         <p className="admin-doc-hint">数字越小越靠前。</p>
                       </div>
 
+                      {typeof editingId === "number" && editingDoc?.creator ? (
+                        <div className="admin-doc-field">
+                          <p className="admin-doc-label">创建者</p>
+                          <a
+                            href={userPath(urlStyle, editingDoc.creator.id)}
+                            target="_blank"
+                            rel="noopener noreferrer"
+                            className="inline-flex items-center gap-2 text-[13px] font-medium max-w-full"
+                            style={{ color: "var(--ink)" }}
+                            title={`@${editingDoc.creator.username}`}
+                          >
+                            <Avatar
+                              size={22}
+                              name={editingDoc.creator.nickname || editingDoc.creator.username}
+                              src={editingDoc.creator.avatar}
+                            />
+                            <span className="truncate">
+                              {editingDoc.creator.nickname || editingDoc.creator.username}
+                            </span>
+                          </a>
+                          <p className="admin-doc-hint">条目创建后归属不变。</p>
+                        </div>
+                      ) : null}
+
                       {/* 附件管理：长列表列内滚动 */}
                       <div className="admin-doc-field flex flex-col lg:flex-1 lg:min-h-0">
                         <p className="admin-doc-label shrink-0">
@@ -956,6 +1145,27 @@ export default function LibraryAdmin({
         </section>
       </div>
 
+      {/* 导入遇到同名书籍：确认后覆盖重传（保留同一 File） */}
+      <ConfirmDialog
+        open={!!importOverwrite}
+        title="覆盖导入同名书籍？"
+        message={
+          importOverwrite
+            ? `备份包中有 ${importOverwrite.count} 本书的地址已被现有书籍占用。选择覆盖将用备份包整体替换这些书籍的介绍、章节、附件与封面，现有内容不可恢复；其余书籍正常新建。`
+            : ""
+        }
+        danger
+        busy={importing}
+        confirmLabel="覆盖导入"
+        cancelLabel="保留现有"
+        onCancel={() => !importing && setImportOverwrite(null)}
+        onConfirm={() => {
+          const pending = importOverwrite;
+          setImportOverwrite(null);
+          if (pending) void runImport(pending.file, "overwrite");
+        }}
+      />
+
       {/* 未保存关闭/切换确认 */}
       <ConfirmDialog
         open={!!pendingNav}