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/presentation/dto/create-payment.dto.ts

@@ -0,0 +1,35 @@
+import {
+  IsEnum,
+  IsOptional,
+  IsString,
+  IsUrl,
+  MinLength,
+} from 'class-validator';
+import { Transform } from 'class-transformer';
+import { PaymentProvider, PaymentType } from '@prisma/client';
+
+export class CreatePaymentDto {
+  @IsEnum(PaymentProvider)
+  provider!: PaymentProvider;
+
+  @IsEnum(PaymentType)
+  type!: PaymentType;
+
+  @Transform(({ value }) => BigInt(value))
+  amountVND!: bigint;
+
+  @IsString()
+  @MinLength(1)
+  description!: string;
+
+  @IsUrl()
+  returnUrl!: string;
+
+  @IsOptional()
+  @IsString()
+  transactionId?: string;
+
+  @IsOptional()
+  @IsString()
+  idempotencyKey?: string;
+}

apps/api/src/modules/payments/presentation/dto/index.ts

@@ -0,0 +1,3 @@
+export { CreatePaymentDto } from './create-payment.dto';
+export { RefundPaymentDto } from './refund-payment.dto';
+export { ListTransactionsDto } from './list-transactions.dto';

apps/api/src/modules/payments/presentation/dto/list-transactions.dto.ts

@@ -0,0 +1,19 @@
+import { IsEnum, IsInt, IsOptional, Max, Min } from 'class-validator';
+import { PaymentStatus } from '@prisma/client';
+
+export class ListTransactionsDto {
+  @IsOptional()
+  @IsEnum(PaymentStatus)
+  status?: PaymentStatus;
+
+  @IsOptional()
+  @IsInt()
+  @Min(1)
+  @Max(100)
+  limit?: number;
+
+  @IsOptional()
+  @IsInt()
+  @Min(0)
+  offset?: number;
+}

apps/api/src/modules/payments/presentation/dto/refund-payment.dto.ts

@@ -0,0 +1,7 @@
+import { IsString, MinLength } from 'class-validator';
+
+export class RefundPaymentDto {
+  @IsString()
+  @MinLength(1)
+  reason!: string;
+}