外观设置改为单页分区；发帖草稿与板块校验优化，WS 延迟释放避开 Strict Mode 误断。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/components/RealtimeProvider.tsx

@@ -9,7 +9,8 @@ export default function RealtimeProvider({ userId }: { userId: number | null })
   useEffect(() => {
     if (userId) {
       realtime.connect();
-      return () => realtime.disconnect();
+      // 用 release 而非立刻 disconnect：避开 Strict Mode / HMR 瞬时卸载打断握手
+      return () => realtime.release();
     }
     realtime.disconnect();
   }, [userId]);