feat: 实时消息与管理端运营能力

新增群聊/私信与公共 WebSocket 总线，站长用户内容档案，并将通知与待审角标改为推送驱动；同步精简管理仪表盘并修复主题换肤 DOM 冲突。

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

frontend/app/layout.tsx

@@ -7,6 +7,7 @@ import Footer from "@/components/Footer";
 import Toaster from "@/components/Toaster";
 import AccountGuard from "@/components/AccountGuard";
 import ThemeSync from "@/components/ThemeSync";
+import RealtimeProvider from "@/components/RealtimeProvider";
 import type { User } from "@/lib/api";
 import { getMeCached, getPublicSettingsCached } from "@/lib/serverData";
 import { TOKEN_COOKIE, REFRESH_COOKIE, authCookieHeader } from "@/lib/cookies";
@@ -68,6 +69,7 @@ export default async function RootLayout({
 
   let user: User | null = null;
   let unread = 0;
+  let chatUnread = 0;
   const hasAuthCookie =
     !!cookieStore.get(TOKEN_COOKIE)?.value || !!cookieStore.get(REFRESH_COOKIE)?.value;
   if (hasAuthCookie) {
@@ -75,6 +77,7 @@ export default async function RootLayout({
     const me = await getMeCached(authCookieHeader(cookieStore) || undefined);
     user = me.user;
     unread = me.unread_count;
+    chatUnread = me.chat_unread_count ?? 0;
   }
 
   return (
@@ -84,7 +87,7 @@ export default async function RootLayout({
     >
       <body className="min-h-screen flex flex-col">
         {accentCSS ? (
-          // id 与 lib/theme 的运行时换肤共用：后台实时预览时直接复用/替换此节点
+          // React 托管的 SSR 主题节点；客户端换肤走 j13-accent-runtime，禁止对此外挂 remove
           <style
             id="j13-accent-vars"
             data-accent-source="ssr"
@@ -94,7 +97,12 @@ export default async function RootLayout({
         <a href="#main" className="skip-link">
           跳到主要内容
         </a>
-        <Header initialUser={user} initialUnread={unread} initialTheme={theme} />
+        <Header
+          initialUser={user}
+          initialUnread={unread}
+          initialChatUnread={chatUnread}
+          initialTheme={theme}
+        />
         <main
           id="main"
           tabIndex={-1}
@@ -106,6 +114,7 @@ export default async function RootLayout({
         <Toaster />
         <AccountGuard />
         <ThemeSync initialAccent={accent || ""} />
+        <RealtimeProvider userId={user ? user.id : null} />
       </body>
     </html>
   );