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

.cursorrules

@@ -0,0 +1,13 @@
+# Global Project Constraints
+
+1. **Language Requirements**: 
+   - All code comments **MUST** be written in **English**.
+   - All server and client logs (`console.log`, `logger.info`, `logger.error`, etc.) **MUST** be written in **English**.
+
+2. **Internationalization (i18n)**:
+   - All user-facing messages, API response messages, error messages, and UI text **MUST** guarantee internationalization support.
+   - Do not use hardcoded string literals for messages. Always use the project's designated i18n service or translation utility with proper keys.
+
+3. **UI Notifications**:
+   - All popup messages, error alerts, and system notifications **MUST** uniformly use the toast component (e.g., via `useToast().showError()`, `showSuccess()`). 
+   - Never use native browser `window.alert()`.