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/migrations/1772340000000-AddParentIdToKnowledgeGroups.ts

@@ -0,0 +1,18 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+
+export class AddParentIdToKnowledgeGroups1772340000000 implements MigrationInterface {
+  name = 'AddParentIdToKnowledgeGroups1772340000000';
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    // Add parent_id column to knowledge_groups table
+    await queryRunner.query(
+      `ALTER TABLE "knowledge_groups" ADD COLUMN "parent_id" text REFERENCES "knowledge_groups"("id") ON DELETE SET NULL`,
+    );
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `ALTER TABLE "knowledge_groups" DROP COLUMN "parent_id"`,
+    );
+  }
+}