feat: implement QuestionBank CRUD with pagination and template query

- Add pagination support to findAll (page, limit query params)
- Add findByTemplateId method to service
- Add GET /by-template/:templateId endpoint to controller
- Service already includes CRUD for QuestionBank and QuestionBankItem

server/src/tenant/tenant.store.ts

@@ -0,0 +1,8 @@
+import { AsyncLocalStorage } from 'async_hooks';
+
+export interface TenantContext {
+  tenantId: string;
+  userId?: string;
+}
+
+export const tenantStore = new AsyncLocalStorage<TenantContext>();