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-member.entity.ts

@@ -0,0 +1,49 @@
+import {
+  Column,
+  CreateDateColumn,
+  Entity,
+  JoinColumn,
+  ManyToOne,
+  PrimaryGeneratedColumn,
+  UpdateDateColumn,
+} from 'typeorm';
+import { User } from '../user/user.entity';
+import { UserRole } from '../user/user-role.enum';
+import { Tenant } from './tenant.entity';
+
+/**
+ * Join table for User and Tenant to support Many-to-Many relationship.
+ * A user can belong to multiple tenants with different roles in each.
+ */
+@Entity('tenant_members')
+export class TenantMember {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column({ name: 'user_id' })
+  userId: string;
+
+  @ManyToOne(() => User, (user) => user.tenantMembers, { onDelete: 'CASCADE' })
+  @JoinColumn({ name: 'user_id' })
+  user: User;
+
+  @Column({ name: 'tenant_id' })
+  tenantId: string;
+
+  @ManyToOne(() => Tenant, (tenant) => tenant.members, { onDelete: 'CASCADE' })
+  @JoinColumn({ name: 'tenant_id' })
+  tenant: Tenant;
+
+  @Column({
+    type: 'simple-enum',
+    enum: UserRole,
+    default: UserRole.USER,
+  })
+  role: UserRole;
+
+  @CreateDateColumn({ name: 'created_at' })
+  createdAt: Date;
+
+  @UpdateDateColumn({ name: 'updated_at' })
+  updatedAt: Date;
+}