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/PostInteractPanels.tsx

@@ -18,6 +18,8 @@ import {
 import { toast } from "@/lib/toast";
 import Avatar from "@/components/Avatar";
 import { useAllowComments } from "@/components/CommentsPolicyProvider";
+import { postPath, userPath } from "@/lib/urlStyle";
+import { useUrlStyle } from "@/components/SiteBrandProvider";
 
 export default function PostInteractPanels({
   postId,
@@ -286,6 +288,7 @@ function PollPanel({
   loggedIn: boolean;
 }) {
   const router = useRouter();
+  const urlStyle = useUrlStyle();
   const [sel, setSel] = useState<number[]>(state.my_options || []);
   const [busy, setBusy] = useState(false);
   const showResults = state.closed || (state.my_options && state.my_options.length > 0);
@@ -418,7 +421,7 @@ function PollPanel({
                 <ul className="j13-poll-voters">
                   {namedVoters.map((v) => (
                     <li key={v.id}>
-                      <Link href={`/u/${v.id}`} className="j13-poll-voter">
+                      <Link href={userPath(urlStyle, v.id)} className="j13-poll-voter">
                         <Avatar name={v.nickname || v.username} src={v.avatar || undefined} size={16} />
                         {v.nickname || v.username}
                       </Link>
@@ -445,7 +448,7 @@ function PollPanel({
           )}
           {!loggedIn && !state.closed && (
             <Link
-              href={`/login?redirect=${encodeURIComponent(`/post/${postId}`)}`}
+              href={`/login?redirect=${encodeURIComponent(postPath(urlStyle, postId))}`}
               className="btn btn-line btn-sm"
             >
               登录后投票
@@ -559,6 +562,7 @@ function LotteryPanel({
   state: LotteryState;
 }) {
   const router = useRouter();
+  const urlStyle = useUrlStyle();
   const [busy, setBusy] = useState(false);
 
   const act = async (fn: () => Promise<{ post?: unknown; error?: string }>, ok: string) => {
@@ -651,7 +655,7 @@ function LotteryPanel({
                       className="j13-lottery-winner-avatar"
                     />
                     <div className="j13-lottery-winner-body">
-                      <Link href={`/u/${w.id}`} className="j13-lottery-winner-name">
+                      <Link href={userPath(urlStyle, w.id)} className="j13-lottery-winner-name">
                         {w.nickname || w.username}
                       </Link>
                       {w.prize_name ? (