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/app/(dashboard)/teacher/dashboard/page.tsx

@@ -7,6 +7,8 @@ import { getAuthContext } from "@/shared/lib/auth-guard"
 
 export const dynamic = "force-dynamic"
 
+export const metadata = { title: "Dashboard - Next_Edu" }
+
 export default async function TeacherDashboardPage(): Promise<JSX.Element> {
   await getAuthContext()
   const teacherId = await getTeacherIdForMutations()