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/announcement/[id]/page.tsx

@@ -1,11 +1,11 @@
 import type { Metadata } from "next";
 import { cookies } from "next/headers";
 import { notFound } from "next/navigation";
-import { Megaphone } from "lucide-react";
+import { Megaphone, Pin } from "lucide-react";
 import { fetchAnnouncementDetail, fetchOverview } from "@/lib/api";
 import { authCookieHeader } from "@/lib/cookies";
 import { getMeCached, getPublicSettingsCached } from "@/lib/serverData";
-import { isAdminOrAbove } from "@/lib/roles";
+import { hasPerm, PERMS } from "@/lib/roles";
 import { extractToc, estimateReadingMinutes, markdownHeadingToc } from "@/lib/toc";
 import MarkdownBody from "@/components/MarkdownBody";
 import PostToc from "@/components/PostToc";
@@ -59,7 +59,7 @@ export default async function AnnouncementPage({ params }: PageProps) {
   const loginHref = `/login?redirect=${encodeURIComponent(`/announcement/${id}`)}`;
   const sidebarPages = overview?.sidebar_pages ?? [];
   const announcements = overview?.announcements ?? [];
-  const canManagePages = !!me.user && isAdminOrAbove(me.user.role);
+  const canManagePages = !!me.user && hasPerm(me.user, PERMS.PAGES);
   const siteLead = settings.site_description?.trim() || undefined;
   const urlStyle = settings.url_style;
   const toc = extractToc(a.content);
@@ -116,7 +116,11 @@ export default async function AnnouncementPage({ params }: PageProps) {
             showTimeOfDay
             badges={
               <>
-                {a.pinned ? <span className="badge-pin">置顶</span> : null}
+                {a.pinned ? (
+                  <span className="badge-pin" title="置顶" aria-label="置顶">
+                    <Pin size={12} fill="currentColor" strokeWidth={2.2} aria-hidden />
+                  </span>
+                ) : null}
                 <span className={`j13-anno-tag is-${a.tag_color}`}>{a.tag}</span>
               </>
             }