feat: 可配置站点 URL 风格

- 新增 urlStyle 工具与测试：postPath/userPath/sitePagePath 统一生成链接
- 管理端新增 UrlStylePanel 设置面板，settings 服务与 handler 适配
- 全站路由链接与 JSON-LD/sitemap 切换为统一 URL 生成
- middleware 与相关组件适配

frontend/components/MobileTabBar.tsx

@@ -12,7 +12,9 @@ import {
 } from "lucide-react";
 import { apiChatUnreadSummary, type User } from "@/lib/api";
 import { useAllowMessages } from "@/components/MessagesPolicyProvider";
+import { useUrlStyle } from "@/components/SiteBrandProvider";
 import { onDocumentVisible } from "@/lib/visibilityReconcile";
+import { parseEntityPath, userPath, leaderboardPath } from "@/lib/urlStyle";
 import { realtime, RT_CHAT_UNREAD } from "@/lib/realtime";
 import type { RtChatUnreadData } from "@/lib/realtime";
 
@@ -30,6 +32,8 @@ export default function MobileTabBar({
 }) {
   const pathname = usePathname();
   const allowMessages = useAllowMessages();
+  const urlStyle = useUrlStyle();
+  const lbHref = leaderboardPath(urlStyle);
   const [chatUnread, setChatUnread] = useState(initialChatUnread);
 
   // 登录态经 router.refresh() 下发新 props 时校正徽标
@@ -96,10 +100,10 @@ export default function MobileTabBar({
           active={isActive((p) => p === "/")}
         />
         <TabLink
-          href="/leaderboard"
+          href={lbHref}
           icon={<Trophy size={20} />}
           label="排行榜"
-          active={isActive((p) => p.startsWith("/leaderboard"))}
+          active={!!pathname && (pathname === lbHref || pathname.startsWith(`${lbHref}/`))}
         />
         <TabLink
           href={user ? "/compose" : "/login"}
@@ -118,11 +122,18 @@ export default function MobileTabBar({
           />
         )}
         <TabLink
-          href={user ? `/u/${user.id}` : "/login"}
+          href={user ? userPath(urlStyle, user.id) : "/login"}
           icon={<UserIcon size={20} />}
           label="我的"
           active={
-            !!user && isActive((p) => p === `/u/${user.id}` || p.startsWith(`/u/${user.id}/`))
+            !!user &&
+            isActive((p) => {
+              const parsed = parseEntityPath(p);
+              return (
+                (parsed?.kind === "user" && parsed.id === user.id) ||
+                p.startsWith(`${userPath(urlStyle, user.id)}/`)
+              );
+            })
           }
         />
       </div>