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/admin/settings/BasicSettings.tsx

@@ -6,6 +6,7 @@ import useUnsavedGuard from "@/hooks/useUnsavedGuard";
 import BasicIdentityPanel from "./BasicIdentityPanel";
 import BrandSeoPanel from "./BrandSeoPanel";
 import FooterLinksPanel from "./FooterLinksPanel";
+import UrlStylePanel from "./UrlStylePanel";
 import type { PublicSettings } from "@/lib/api";
 
 export default function BasicSettings({ initial }: { initial: PublicSettings }) {
@@ -13,17 +14,20 @@ export default function BasicSettings({ initial }: { initial: PublicSettings })
   const [basicDirty, setBasicDirty] = useState(false);
   const [brandDirty, setBrandDirty] = useState(false);
   const [seoDirty, setSeoDirty] = useState(false);
-  const dirty = basicDirty || brandDirty || seoDirty;
+  const [urlStyleDirty, setUrlStyleDirty] = useState(false);
+  const dirty = basicDirty || brandDirty || seoDirty || urlStyleDirty;
   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), []);
 
   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} />
       <FooterLinksPanel initial={live} onSaved={setLive} onDirtyChange={onSeoDirty} />
       <ConfirmDialog
         open={leave.leaveOpen}