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)/messages/[id]/loading.tsx

@@ -0,0 +1,43 @@
+import { Card, CardContent, CardHeader } from "@/shared/components/ui/card"
+import { Skeleton } from "@/shared/components/ui/skeleton"
+import { Button } from "@/shared/components/ui/button"
+
+export default function MessageDetailLoading() {
+  return (
+    <div className="flex h-full flex-col p-8">
+      <div className="mx-auto w-full max-w-3xl space-y-6">
+        <div className="flex items-center gap-4">
+          <Skeleton className="h-9 w-24" />
+          <div className="space-y-2">
+            <Skeleton className="h-7 w-64" />
+            <Skeleton className="h-4 w-48" />
+          </div>
+        </div>
+
+        <Card>
+          <CardHeader className="space-y-2">
+            <Skeleton className="h-5 w-3/4" />
+            <div className="flex items-center gap-2">
+              <Skeleton className="h-3 w-24" />
+              <Skeleton className="h-3 w-32" />
+            </div>
+          </CardHeader>
+          <CardContent className="space-y-3">
+            {Array.from({ length: 6 }).map((_, i) => (
+              <Skeleton key={i} className="h-4 w-full" />
+            ))}
+          </CardContent>
+        </Card>
+
+        <div className="flex justify-between">
+          <Button variant="outline" disabled>
+            <Skeleton className="h-4 w-20" />
+          </Button>
+          <Button disabled>
+            <Skeleton className="h-4 w-24" />
+          </Button>
+        </div>
+      </div>
+    </div>
+  )
+}

src/app/(dashboard)/messages/compose/loading.tsx

@@ -0,0 +1,40 @@
+import { Card, CardContent, CardHeader } from "@/shared/components/ui/card"
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function ComposeLoading() {
+  return (
+    <div className="flex h-full flex-col p-8">
+      <div className="mx-auto w-full max-w-3xl space-y-6">
+        <div className="space-y-2">
+          <Skeleton className="h-8 w-48" />
+          <Skeleton className="h-4 w-64" />
+        </div>
+
+        <Card>
+          <CardHeader>
+            <Skeleton className="h-5 w-32" />
+          </CardHeader>
+          <CardContent className="space-y-4">
+            <div className="space-y-2">
+              <Skeleton className="h-4 w-16" />
+              <Skeleton className="h-10 w-full" />
+            </div>
+            <div className="space-y-2">
+              <Skeleton className="h-4 w-20" />
+              <Skeleton className="h-10 w-full" />
+            </div>
+            <div className="space-y-2">
+              <Skeleton className="h-4 w-16" />
+              <Skeleton className="h-32 w-full" />
+            </div>
+          </CardContent>
+        </Card>
+
+        <div className="flex justify-end gap-3">
+          <Skeleton className="h-10 w-24" />
+          <Skeleton className="h-10 w-28" />
+        </div>
+      </div>
+    </div>
+  )
+}

src/app/(dashboard)/messages/error.tsx

@@ -0,0 +1,22 @@
+"use client"
+
+import { AlertCircle } from "lucide-react"
+
+import { EmptyState } from "@/shared/components/ui/empty-state"
+
+export default function MessagesError({ reset }: { error: Error & { digest?: string }; reset: () => void }) {
+  return (
+    <div className="flex h-full flex-col items-center justify-center space-y-4 p-8">
+      <EmptyState
+        icon={AlertCircle}
+        title="消息加载失败"
+        description="抱歉，加载消息时发生了意外错误。请稍后重试。"
+        action={{
+          label: "重试",
+          onClick: () => reset(),
+        }}
+        className="border-none shadow-none h-auto"
+      />
+    </div>
+  )
+}

src/app/(dashboard)/messages/loading.tsx

@@ -0,0 +1,36 @@
+import { Card, CardContent, CardHeader } from "@/shared/components/ui/card"
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function MessagesLoading() {
+  return (
+    <div className="flex h-full flex-col space-y-8 p-8">
+      <div className="space-y-2">
+        <Skeleton className="h-8 w-48" />
+        <Skeleton className="h-4 w-64" />
+      </div>
+
+      <div className="space-y-4">
+        <div className="flex items-center justify-between">
+          <Skeleton className="h-10 w-48" />
+          <Skeleton className="h-10 w-28" />
+        </div>
+        <Skeleton className="h-10 w-full" />
+        {Array.from({ length: 5 }).map((_, i) => (
+          <Card key={i}>
+            <CardHeader className="flex flex-row items-start justify-between gap-2 space-y-0 pb-3">
+              <div className="space-y-2">
+                <Skeleton className="h-4 w-48" />
+                <Skeleton className="h-3 w-32" />
+              </div>
+              <Skeleton className="h-3 w-20" />
+            </CardHeader>
+            <CardContent className="pt-0">
+              <Skeleton className="h-4 w-full" />
+              <Skeleton className="mt-1 h-4 w-3/4" />
+            </CardContent>
+          </Card>
+        ))}
+      </div>
+    </div>
+  )
+}