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/chat/[id]/ChatRoomClient.tsx

@@ -56,6 +56,8 @@ import AutolinkText from "@/components/AutolinkText";
 import ConfirmDialog from "@/components/ConfirmDialog";
 import ContextMenu, { type CtxMenuItem } from "@/components/ContextMenu";
 import ChatUserCard, { type ChatUserCardTarget } from "@/components/ChatUserCard";
+import { userPath } from "@/lib/urlStyle";
+import { useUrlStyle } from "@/components/SiteBrandProvider";
 
 /** 同一房间已读：进行中去重 + 2s 内合并（滚动/新消息/Strict Mode 连打） */
 const MARK_READ_GAP_MS = 2_000;
@@ -102,6 +104,7 @@ function RecallNotice({
   meId: number;
   members: ChatRoomMember[];
 }) {
+  const urlStyle = useUrlStyle();
   if (!message.recalled_at) return null;
   const by =
     message.recalled_by ||
@@ -137,7 +140,7 @@ function RecallNotice({
   const nameNode =
     uid > 0 ? (
       <Link
-        href={`/u/${uid}`}
+        href={userPath(urlStyle, uid)}
         className="transition-opacity hover:opacity-80"
         style={nameStyle}
       >
@@ -2020,6 +2023,7 @@ function MembersPanel({
   onOpenCard: (m: ChatRoomMember) => void;
   showTitle?: boolean;
 }) {
+  const urlStyle = useUrlStyle();
   return (
     <div>
       {showTitle && (
@@ -2072,7 +2076,7 @@ function MembersPanel({
                 <Avatar name={name} src={m.user.avatar || undefined} size={28} />
               </button>
               <Link
-                href={`/u/${m.user.id}`}
+                href={userPath(urlStyle, m.user.id)}
                 className="flex-1 min-w-0 truncate text-[13px] hover:text-[var(--accent)] transition-colors"
                 style={{ color: "var(--ink)" }}
               >