feat(app): add error/loading boundaries and update dashboard routes

- Add error.tsx and loading.tsx boundaries for admin, parent, student, teacher routes

- Add dashboard-error-fallback and dashboard-loading-skeleton components

- Add student/learning page, parent/leave routes, teacher textbook components

- Update existing app routes across auth, dashboard, and API endpoints

- Update proxy middleware and next-auth type declarations

src/app/(dashboard)/teacher/diagnostic/class/[classId]/page.tsx

@@ -5,6 +5,7 @@ import { requirePermission } from "@/shared/lib/auth-guard"
 import { Permissions } from "@/shared/types/permissions"
 import { getClassMasterySummary } from "@/modules/diagnostic/data-access"
 import { ClassDiagnosticView } from "@/modules/diagnostic/components/class-diagnostic-view"
+import { WidgetBoundary } from "@/modules/grades/components/widget-boundary"
 
 export const dynamic = "force-dynamic"
 
@@ -41,7 +42,9 @@ export default async function ClassDiagnosticPage({
           Class-level knowledge point mastery overview and student attention list.
         </p>
       </div>
-      <ClassDiagnosticView summary={summary} />
+      <WidgetBoundary title="班级学情诊断" skeletonHeight={400}>
+        <ClassDiagnosticView summary={summary} />
+      </WidgetBoundary>
     </div>
   )
 }