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/textbooks/page.tsx

@@ -8,6 +8,8 @@ import { getTextbooks } from "@/modules/textbooks/data-access"
 import { TextbookFilters } from "@/modules/textbooks/components/textbook-filters"
 import { EmptyState } from "@/shared/components/ui/empty-state"
 import { getParam, type SearchParams } from "@/shared/lib/search-params"
+import { requirePermission } from "@/shared/lib/auth-guard"
+import { Permissions } from "@/shared/types/permissions"
 
 export const dynamic = "force-dynamic"
 
@@ -18,6 +20,8 @@ async function TextbooksResults({
   searchParams: Promise<SearchParams>
   t: Awaited<ReturnType<typeof getTranslations<"textbooks">>>
 }): Promise<JSX.Element> {
+  await requirePermission(Permissions.TEXTBOOK_READ)
+
   const params = await searchParams
 
   const q = getParam(params, "q") || undefined