fix: patch P0 security vulnerabilities and critical UX issues across 6 modules

Security: Add admin/layout.tsx auth guard; Add requirePermission() to 12 admin pages

Dashboard: Fix StudentStatsGrid rendering; Fix teacher greeting; Add loading/error boundaries; Fix col-span; Add metadata

Announcements: Fix audience filtering; Add user detail page; Trigger notifications on publish; Pass classes data; Add loading.tsx

Messages: Implement soft delete; Add unread badge with polling; Add notification dropdown polling; Add keyword search; Add quiet hours DND

Management: Add loading/error for 9 admin routes; Fix admin-classes-view to use Select for school/grade

Profile/Settings: Add loading/error; Fix parent role routing; Create ParentSettingsView; Integrate AiProviderSettingsCard; Add Tab URL persistence; Add logout confirm; Add avatar; Fix Progress arbitrary class

Schema: Add senderDeletedAt/receiverDeletedAt to messages; Add quietHours to notificationPreferences; Add uniqueIndex import

Docs: Update architecture docs 004/005

src/modules/messaging/components/notification-dropdown.tsx

@@ -20,6 +20,7 @@ import { cn, formatDate } from "@/shared/lib/utils"
 
 import {
   getNotificationsAction,
+  getUnreadNotificationCountAction,
   markAllNotificationsAsReadAction,
   markNotificationAsReadAction,
 } from "../actions"
@@ -40,16 +41,35 @@ export function NotificationDropdown() {
 
   useEffect(() => {
     let active = true
-    void (async () => {
+
+    const fetchNotifications = async () => {
       const res = await getNotificationsAction({ pageSize: 10 })
       if (!active) return
       if (res.success && res.data) {
         setNotifications(res.data.items)
-        setUnreadCount(res.data.items.filter((n) => !n.isRead).length)
       }
-    })()
+    }
+
+    const fetchUnreadCount = async () => {
+      const res = await getUnreadNotificationCountAction()
+      if (!active) return
+      if (res.success && typeof res.data === "number") {
+        setUnreadCount(res.data)
+      }
+    }
+
+    void fetchNotifications()
+    void fetchUnreadCount()
+
+    // 每 30 秒轮询刷新通知和未读计数
+    const timer = setInterval(() => {
+      void fetchNotifications()
+      void fetchUnreadCount()
+    }, 30_000)
+
     return () => {
       active = false
+      clearInterval(timer)
     }
   }, [])