feat: 友链/书库/移动端导航/排行榜等多模块功能

新增模块：
- 友链（friendlink）后端处理 + 前端管理页与友链板
- 书库（library）：导入、章节、封面、阅读页、横竖版自适应 AdaptiveCoverSlot
- 顶栏导航（header_nav）配置与 MobileTabBar/MobileRailDrawers 移动端抽屉
- 排行榜 service 测试、站点页面测试、时间线发布（timeline_release）

其它改动：
- 后端 handlers/services 全量小幅调整
- 前端组件、库函数、URL/品牌/站点 URL 工具更新
- Lightbox 图片、MdEntries 条目卡、coverColor 派生色相等前端能力

frontend/app/admin/settings/BasicSettings.tsx

@@ -6,6 +6,8 @@ import useUnsavedGuard from "@/hooks/useUnsavedGuard";
 import BasicIdentityPanel from "./BasicIdentityPanel";
 import BrandSeoPanel from "./BrandSeoPanel";
 import FooterLinksPanel from "./FooterLinksPanel";
+import HeaderNavPanel from "./HeaderNavPanel";
+import MobileTabBarPanel from "./MobileTabBarPanel";
 import UrlStylePanel from "./UrlStylePanel";
 import type { PublicSettings } from "@/lib/api";
 
@@ -15,19 +17,25 @@ export default function BasicSettings({ initial }: { initial: PublicSettings })
   const [brandDirty, setBrandDirty] = useState(false);
   const [seoDirty, setSeoDirty] = useState(false);
   const [urlStyleDirty, setUrlStyleDirty] = useState(false);
-  const dirty = basicDirty || brandDirty || seoDirty || urlStyleDirty;
+  const [mobileTabsDirty, setMobileTabsDirty] = useState(false);
+  const [headerNavDirty, setHeaderNavDirty] = useState(false);
+  const dirty = basicDirty || brandDirty || seoDirty || urlStyleDirty || mobileTabsDirty || headerNavDirty;
   const leave = useUnsavedGuard(dirty);
 
   const onBasicDirty = useCallback((d: boolean) => setBasicDirty(d), []);
   const onBrandDirty = useCallback((d: boolean) => setBrandDirty(d), []);
   const onSeoDirty = useCallback((d: boolean) => setSeoDirty(d), []);
   const onUrlStyleDirty = useCallback((d: boolean) => setUrlStyleDirty(d), []);
+  const onMobileTabsDirty = useCallback((d: boolean) => setMobileTabsDirty(d), []);
+  const onHeaderNavDirty = useCallback((d: boolean) => setHeaderNavDirty(d), []);
 
   return (
     <div className="admin-settings-stack">
       <BasicIdentityPanel initial={live} onSaved={setLive} onDirtyChange={onBasicDirty} />
       <BrandSeoPanel initial={live} onSaved={setLive} onDirtyChange={onBrandDirty} />
       <UrlStylePanel initial={live} onSaved={setLive} onDirtyChange={onUrlStyleDirty} />
+      <HeaderNavPanel initial={live} onSaved={setLive} onDirtyChange={onHeaderNavDirty} />
+      <MobileTabBarPanel initial={live} onSaved={setLive} onDirtyChange={onMobileTabsDirty} />
       <FooterLinksPanel initial={live} onSaved={setLive} onDirtyChange={onSeoDirty} />
       <ConfirmDialog
         open={leave.leaveOpen}