feat: 站点媒体库与移动端底部导航，服务测试补强

- 新增媒体库：media_library/media_thumbs 服务（WebP 缩略图）、管理端 media 页面
- 移动端底部导航 MobileTabBar 替换 MobilePostBar
- 旧数据导入增强与测试、路由与登录会话/板块侧边栏测试补强
- site-doc 组件精简（移除 Breadcrumb），文档新增迁移公告说明

frontend/components/home/WorkspaceNav.tsx

@@ -2,7 +2,8 @@
 
 import Link from "next/link";
 import { useSearchParams } from "next/navigation";
-import { PenSquare, Home, LayoutGrid, ShieldCheck } from "lucide-react";
+import { useCallback, useEffect, useRef, useState } from "react";
+import { Bookmark, Home, ShieldCheck } from "lucide-react";
 import type { BoardWithCount, User } from "@/lib/api";
 import { isStaff } from "@/lib/roles";
 import BoardIcon, { boardColor } from "@/components/BoardIcon";
@@ -27,17 +28,8 @@ export function WorkspaceNavPanel({
 
   return (
     <section className="j13-module flex max-h-[var(--rail-max-h)] flex-col overflow-hidden" aria-label="板块目录">
-      <p className="j13-module-title shrink-0">
-        <LayoutGrid size={15} style={{ color: "var(--accent)" }} aria-hidden />
-        板块目录
-        {boards.length > 0 ? (
-          <span className="ml-auto meta text-[11.5px] font-medium tracking-normal tabular-nums">
-            {boards.length} 个
-          </span>
-        ) : null}
-      </p>
-
-      <div className="j13-rail-scroll j13-board-list mt-2.5 min-h-0 flex-1">
+      <div className="j13-rail-scroll j13-board-list min-h-0 flex-1">
+        <p className="j13-rail-group">浏览</p>
         <Link
           href="/"
           className="j13-bcard"
@@ -53,25 +45,41 @@ export function WorkspaceNavPanel({
           <span className="j13-bcard-name flex-1 truncate">全部讨论</span>
         </Link>
 
-        {boards.length > 0 ? <div className="j13-board-split" role="separator" /> : null}
-
-        {boards.map((b) => (
-          <Link
-            key={b.id}
-            href={boardHref(b.id)}
-            className="j13-bcard"
-            aria-current={activeBoard === b.id ? "page" : undefined}
-            aria-label={`${b.name}板块，${b.post_count} 篇讨论`}
-          >
-            <span className={`av-${boardColor(b)} j13-bcard-ico`} aria-hidden="true">
-              <BoardIcon icon={b.icon} name={b.name} size={15} />
-            </span>
-            <span className="min-w-0 flex-1 flex items-center justify-between gap-2">
-              <span className="j13-bcard-name truncate">{b.name}</span>
-              <span className="meta shrink-0 text-[11px] tabular-nums">{b.post_count} 篇</span>
+        {user ? (
+          <Link href={`/u/${user.id}?tab=favorites`} className="j13-bcard">
+            <span
+              className="j13-bcard-ico"
+              style={{ background: "var(--accent-soft)", color: "var(--accent)" }}
+              aria-hidden="true"
+            >
+              <Bookmark size={15} />
             </span>
+            <span className="j13-bcard-name flex-1 truncate">我的收藏</span>
           </Link>
-        ))}
+        ) : null}
+
+        {boards.length > 0 ? (
+          <>
+            <p className="j13-rail-group">板块</p>
+            {boards.map((b) => (
+              <Link
+                key={b.id}
+                href={boardHref(b.id)}
+                className="j13-bcard"
+                aria-current={activeBoard === b.id ? "page" : undefined}
+                aria-label={`${b.name}板块，${b.post_count} 篇讨论`}
+              >
+                <span className={`av-${boardColor(b)} j13-bcard-ico`} aria-hidden="true">
+                  <BoardIcon icon={b.icon} name={b.name} size={15} />
+                </span>
+                <span className="min-w-0 flex-1 flex items-center justify-between gap-2">
+                  <span className="j13-bcard-name truncate">{b.name}</span>
+                  <span className="meta shrink-0 text-[11px] tabular-nums">{b.post_count} 篇</span>
+                </span>
+              </Link>
+            ))}
+          </>
+        ) : null}
       </div>
 
       {showAdmin ? (
@@ -105,46 +113,77 @@ export function WorkspaceNav({ boards, user }: { boards: BoardWithCount[]; user?
   );
 }
 
-// 移动端：发帖入口 + 横向滑动板块条
-export function WorkspaceNavMobile({
-  boards,
-  user,
-}: {
-  boards: BoardWithCount[];
-  user: User | null;
-}) {
+// 移动端：横向滑动板块条（两端渐隐指示「可左右滑动」）；发帖入口由底部公共菜单承载
+export function WorkspaceNavMobile({ boards }: { boards: BoardWithCount[] }) {
   const params = useSearchParams();
   const activeBoard = Number(params.get("board")) || 0;
-  const composePath =
-    activeBoard > 0 ? `/compose?board=${activeBoard}` : "/compose";
-  const composeHref = user
-    ? composePath
-    : `/login?redirect=${encodeURIComponent(composePath)}`;
+  const scrollRef = useRef<HTMLDivElement>(null);
+  const [canScrollLeft, setCanScrollLeft] = useState(false);
+  const [canScrollRight, setCanScrollRight] = useState(false);
+
+  const updateScrollState = useCallback(() => {
+    const el = scrollRef.current;
+    if (!el) return;
+    const max = el.scrollWidth - el.clientWidth;
+    setCanScrollLeft(el.scrollLeft > 4);
+    setCanScrollRight(max > 4 && el.scrollLeft < max - 4);
+  }, []);
+
+  useEffect(() => {
+    updateScrollState();
+    const el = scrollRef.current;
+    if (!el || typeof ResizeObserver === "undefined") return;
+    const ro = new ResizeObserver(updateScrollState);
+    ro.observe(el);
+    return () => ro.disconnect();
+  }, [boards, updateScrollState]);
+
+  // 进页 / 切板块时把激活 chip 滚到可视区中央
+  useEffect(() => {
+    const el = scrollRef.current;
+    if (!el) return;
+    el.querySelector<HTMLElement>('[aria-current="page"]')?.scrollIntoView({
+      block: "nearest",
+      inline: "center",
+    });
+  }, [activeBoard, boards]);
 
   return (
-    <div className="lg:hidden -mx-4 sm:-mx-6 px-4 sm:px-6">
-      <div className="j13-chips">
-        <Link href={composeHref} className="btn btn-primary btn-sm shrink-0">
-          <PenSquare size={14} /> 发帖
-        </Link>
-        <Link
-          href="/"
-          className="j13-chip"
-          aria-current={activeBoard === 0 ? "page" : undefined}
+    <div className="lg:hidden -mx-4 sm:-mx-6 px-4 sm:px-6 bg-[var(--main-bg)] border-b border-[var(--line)] py-2.5">
+      <div className="relative">
+        <div
+          ref={scrollRef}
+          className="j13-chips"
+          onScroll={updateScrollState}
         >
-          <Home size={13} /> 全部
-        </Link>
-        {boards.map((b) => (
           <Link
-            key={b.id}
-            href={boardHref(b.id)}
+            href="/"
             className="j13-chip"
-            aria-current={activeBoard === b.id ? "page" : undefined}
+            aria-current={activeBoard === 0 ? "page" : undefined}
           >
-            <BoardIcon icon={b.icon} name={b.name} size={13} />
-            {b.name}
+            <Home size={13} /> 全部
           </Link>
-        ))}
+          {boards.map((b) => (
+            <Link
+              key={b.id}
+              href={boardHref(b.id)}
+              className="j13-chip"
+              aria-current={activeBoard === b.id ? "page" : undefined}
+            >
+              <BoardIcon icon={b.icon} name={b.name} size={13} />
+              {b.name}
+            </Link>
+          ))}
+        </div>
+        {/* 渐隐滑动指示：遮罩与背景同色，pointer-events-none 不挡触控 */}
+        <div
+          className={`j13-chip-fade j13-chip-fade-left ${canScrollLeft ? "is-on" : ""}`}
+          aria-hidden="true"
+        />
+        <div
+          className={`j13-chip-fade j13-chip-fade-right ${canScrollRight ? "is-on" : ""}`}
+          aria-hidden="true"
+        />
       </div>
     </div>
   );