feat(payments): implement Payments module with VNPay, MoMo, ZaloPay integration

Implement complete payment processing module following DDD + CQRS patterns:

- Domain layer: PaymentEntity aggregate, Money value object, domain events
- Infrastructure: PrismaPaymentRepository, VnpayService, MomoService, ZalopayService
- PaymentGatewayFactory pattern for provider abstraction
- CQRS Commands: CreatePayment, HandleCallback, RefundPayment
- CQRS Queries: GetPaymentStatus, ListTransactions
- Callback/webhook endpoints with signature verification and idempotency
- 23 unit tests covering domain, VNPay service, and gateway factory

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/modules/payments/payments.module.ts

@@ -0,0 +1,54 @@
+import { Module } from '@nestjs/common';
+import { CqrsModule } from '@nestjs/cqrs';
+
+// Domain
+import { PAYMENT_REPOSITORY } from './domain/repositories/payment.repository';
+
+// Infrastructure
+import { PrismaPaymentRepository } from './infrastructure/repositories/prisma-payment.repository';
+import { PAYMENT_GATEWAY_FACTORY } from './infrastructure/services/payment-gateway.interface';
+import { PaymentGatewayFactory } from './infrastructure/services/payment-gateway.factory';
+import { VnpayService } from './infrastructure/services/vnpay.service';
+import { MomoService } from './infrastructure/services/momo.service';
+import { ZalopayService } from './infrastructure/services/zalopay.service';
+
+// Application — Commands
+import { CreatePaymentHandler } from './application/commands/create-payment/create-payment.handler';
+import { HandleCallbackHandler } from './application/commands/handle-callback/handle-callback.handler';
+import { RefundPaymentHandler } from './application/commands/refund-payment/refund-payment.handler';
+
+// Application — Queries
+import { GetPaymentStatusHandler } from './application/queries/get-payment-status/get-payment-status.handler';
+import { ListTransactionsHandler } from './application/queries/list-transactions/list-transactions.handler';
+
+// Presentation
+import { PaymentsController } from './presentation/controllers/payments.controller';
+
+const CommandHandlers = [
+  CreatePaymentHandler,
+  HandleCallbackHandler,
+  RefundPaymentHandler,
+];
+
+const QueryHandlers = [GetPaymentStatusHandler, ListTransactionsHandler];
+
+@Module({
+  imports: [CqrsModule],
+  controllers: [PaymentsController],
+  providers: [
+    // Repositories
+    { provide: PAYMENT_REPOSITORY, useClass: PrismaPaymentRepository },
+
+    // Gateway Services
+    VnpayService,
+    MomoService,
+    ZalopayService,
+    { provide: PAYMENT_GATEWAY_FACTORY, useClass: PaymentGatewayFactory },
+
+    // CQRS
+    ...CommandHandlers,
+    ...QueryHandlers,
+  ],
+  exports: [PAYMENT_REPOSITORY, PAYMENT_GATEWAY_FACTORY],
+})
+export class PaymentsModule {}