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/PostComposer.tsx

@@ -35,6 +35,8 @@ import DeadlinePicker, {
 } from "@/components/DeadlinePicker";
 import Modal from "@/components/Modal";
 import { realtime, RT_SETTINGS_CHANGED, type RtSettingsData } from "@/lib/realtime";
+import { postPath } from "@/lib/urlStyle";
+import { useUrlStyle } from "@/components/SiteBrandProvider";
 
 const TITLE_MAX = 256;
 /** 帖子正文字符上限（与后端 handler/post.go 校验一致） */
@@ -179,6 +181,7 @@ export type PostComposerProps = CreateProps | EditProps;
 
 export default function PostComposer(props: PostComposerProps) {
   const router = useRouter();
+  const urlStyle = useUrlStyle();
   const isCreate = props.mode === "create";
 
   const [boards, setBoards] = useState<Board[]>([]);
@@ -828,7 +831,7 @@ export default function PostComposer(props: PostComposerProps) {
           } else {
             toast("发布成功", "ok");
           }
-          router.push(`/post/${res.post.id}`);
+          router.push(postPath(urlStyle, res.post.id));
         } else {
           const mapped = mapPostError(res.error || "发帖失败");
           reportSubmitError(