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/app/settings/page.tsx

@@ -1,7 +1,8 @@
 import { cookies } from "next/headers";
 import { redirect } from "next/navigation";
 import { authCookieHeader } from "@/lib/cookies";
-import { getMeCached } from "@/lib/serverData";
+import { getMeCached, getPublicSettingsCached } from "@/lib/serverData";
+import { userPath } from "@/lib/urlStyle";
 
 // /settings 已融合到用户主页 /u/[id]?tab=settings
 // 未登录跳登录页，登录后跳自己的主页 settings tab
@@ -11,5 +12,6 @@ export default async function SettingsRedirect() {
   if (!me.user) {
     redirect(`/login?redirect=${encodeURIComponent(`/settings`)}`);
   }
-  redirect(`/u/${me.user.id}?tab=settings`);
+  const urlStyle = (await getPublicSettingsCached()).url_style;
+  redirect(`${userPath(urlStyle, me.user.id)}?tab=settings`);
 }