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/Header.tsx

@@ -21,6 +21,7 @@ import {
 } from "lucide-react";
 import { apiLogout, apiMe, apiChatUnreadSummary, type User } from "@/lib/api";
 import { hasAuthCookieHint } from "@/lib/cookies";
+import { userPath } from "@/lib/urlStyle";
 import { canAccessAdminMessages, isStaff } from "@/lib/roles";
 import { onUserUpdate, onForceLogout } from "@/lib/userEvents";
 import { realtime, RT_CHAT_UNREAD } from "@/lib/realtime";
@@ -33,6 +34,8 @@ import LevelBadge from "./LevelBadge";
 import BadgeChip from "./BadgeChip";
 import BrandLockup from "./BrandLockup";
 import { useAllowMessages } from "./MessagesPolicyProvider";
+import { useUrlStyle } from "./SiteBrandProvider";
+import { leaderboardPath } from "@/lib/urlStyle";
 import type { BrandLogoFit, BrandLogoSize, BrandMark } from "@/lib/brand";
 
 export default function Header({
@@ -62,6 +65,8 @@ export default function Header({
 }) {
   const router = useRouter();
   const pathname = usePathname();
+  const urlStyle = useUrlStyle();
+  const lbHref = leaderboardPath(urlStyle);
   const allowMessages = useAllowMessages();
   const hideComposeNav =
     pathname === "/compose" ||
@@ -239,8 +244,8 @@ export default function Header({
               首页
             </NavPill>
             <NavPill
-              href="/leaderboard"
-              active={pathname?.startsWith("/leaderboard") ?? false}
+              href={lbHref}
+              active={!!pathname && (pathname === lbHref || pathname.startsWith(`${lbHref}/`))}
               icon={<Trophy size={15} />}
             >
               排行榜
@@ -410,6 +415,7 @@ function NavPill({
  * 把零散的图标按钮收拢为一个语义明确的控件；移动端只显示头像
  */
 function UserMenu({ user, onLogout }: { user: User; onLogout: () => void }) {
+  const urlStyle = useUrlStyle();
   const [open, setOpen] = useState(false);
   const menuRef = useRef<HTMLDivElement>(null);
 
@@ -493,7 +499,7 @@ function UserMenu({ user, onLogout }: { user: User; onLogout: () => void }) {
             <Link href="/notifications" onClick={() => setOpen(false)} className={itemCls} role="menuitem">
               <Bell size={15} style={{ color: "var(--ink-3)" }} /> 通知中心
             </Link>
-            <Link href={`/u/${user.id}`} onClick={() => setOpen(false)} className={itemCls} role="menuitem">
+            <Link href={userPath(urlStyle, user.id)} onClick={() => setOpen(false)} className={itemCls} role="menuitem">
               <UserIcon size={15} style={{ color: "var(--ink-3)" }} /> 个人主页
             </Link>
             <Link href="/settings" onClick={() => setOpen(false)} className={itemCls} role="menuitem">