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/dashboard/components/teacher-dashboard/teacher-dashboard-header.tsx

@@ -1,3 +1,6 @@
+"use client"
+
+import { formatLongDate } from "@/shared/lib/utils"
 import { TeacherQuickActions } from "./teacher-quick-actions"
 
 interface TeacherDashboardHeaderProps {
@@ -5,18 +8,18 @@ interface TeacherDashboardHeaderProps {
 }
 
 export function TeacherDashboardHeader({ teacherName }: TeacherDashboardHeaderProps) {
-  const today = new Date().toLocaleDateString("en-US", {
-    weekday: "long",
-    year: "numeric",
-    month: "long",
-    day: "numeric",
-  })
+  const today = formatLongDate(new Date())
+  const hour = new Date().getHours()
+  let greeting = "欢迎回来"
+  if (hour < 12) greeting = "早上好"
+  else if (hour < 18) greeting = "下午好"
+  else greeting = "晚上好"
 
   return (
     <div className="flex flex-col justify-between space-y-4 md:flex-row md:items-center md:space-y-0">
       <div>
-        <h2 className="text-2xl font-bold tracking-tight">Good morning, {teacherName}</h2>
-        <p className="text-muted-foreground">It&apos;s {today}. Here&apos;s your daily overview.</p>
+        <h2 className="text-2xl font-bold tracking-tight">{greeting}，{teacherName}</h2>
+        <p className="text-muted-foreground">今天是 {today}，以下是今日概览。</p>
       </div>
       <TeacherQuickActions />
     </div>