fix(web): wire up next-intl i18n — install dep, add locale middleware, wrap next config

The i18n architecture (config, routing, translation files, locale pages) was
already built but non-functional due to three missing pieces:
1. next-intl not listed in package.json
2. middleware.ts not using createMiddleware from next-intl/middleware
3. next.config.js not wrapped with createNextIntlPlugin

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

apps/api/src/modules/payments/domain/__tests__/payment.entity.spec.ts

@@ -95,23 +95,30 @@ describe('PaymentEntity', () => {
 
   it('should not complete an already completed payment', () => {
     const payment = createPayment('COMPLETED');
-    expect(() => payment.markCompleted({})).toThrow('Cannot complete payment');
+    const result = payment.markCompleted({});
+    expect(result.isErr).toBe(true);
+    expect(result.unwrapErr().message).toContain('Cannot complete payment');
   });
 
   it('should not fail an already completed payment', () => {
     const payment = createPayment('COMPLETED');
-    expect(() => payment.markFailed({})).toThrow('Cannot fail payment');
+    const result = payment.markFailed({});
+    expect(result.isErr).toBe(true);
+    expect(result.unwrapErr().message).toContain('Cannot fail payment');
   });
 
   it('should mark completed payment as refunded', () => {
     const payment = createPayment('COMPLETED');
-    payment.markRefunded();
+    const result = payment.markRefunded();
+    expect(result.isOk).toBe(true);
     expect(payment.status).toBe('REFUNDED');
   });
 
   it('should not refund a non-completed payment', () => {
     const payment = createPayment();
-    expect(() => payment.markRefunded()).toThrow('hoàn tiền');
+    const result = payment.markRefunded();
+    expect(result.isErr).toBe(true);
+    expect(result.unwrapErr().message).toContain('hoàn tiền');
   });
 
   it('should store idempotency key', () => {

apps/api/src/modules/payments/domain/entities/payment.entity.ts

@@ -1,9 +1,10 @@
+import { HttpStatus } from '@nestjs/common';
 import {
   type PaymentProvider,
   type PaymentStatus,
   type PaymentType,
 } from '@prisma/client';
-import { AggregateRoot } from '@modules/shared/domain/aggregate-root';
+import { AggregateRoot, DomainException, ErrorCode, Result } from '@modules/shared';
 import { PaymentCompletedEvent } from '../events/payment-completed.event';
 import { PaymentCreatedEvent } from '../events/payment-created.event';
 import { PaymentFailedEvent } from '../events/payment-failed.event';
@@ -89,9 +90,15 @@ export class PaymentEntity extends AggregateRoot<string> {
     this.updatedAt = new Date();
   }
 
-  markCompleted(callbackData: unknown): void {
+  markCompleted(callbackData: unknown): Result<void, DomainException> {
     if (this._status !== 'PENDING' && this._status !== 'PROCESSING') {
-      throw new Error(`Cannot complete payment in status ${this._status}`);
+      return Result.err(
+        new DomainException(
+          ErrorCode.PAYMENT_ALREADY_PROCESSED,
+          `Cannot complete payment in status ${this._status}`,
+          HttpStatus.CONFLICT,
+        ),
+      );
     }
     this._status = 'COMPLETED';
     this._callbackData = callbackData;
@@ -100,11 +107,18 @@ export class PaymentEntity extends AggregateRoot<string> {
     this.addDomainEvent(
       new PaymentCompletedEvent(this.id, this._userId, this._provider, this._amount.value),
     );
+    return Result.ok(undefined);
   }
 
-  markFailed(callbackData: unknown): void {
+  markFailed(callbackData: unknown): Result<void, DomainException> {
     if (this._status !== 'PENDING' && this._status !== 'PROCESSING') {
-      throw new Error(`Cannot fail payment in status ${this._status}`);
+      return Result.err(
+        new DomainException(
+          ErrorCode.PAYMENT_ALREADY_PROCESSED,
+          `Cannot fail payment in status ${this._status}`,
+          HttpStatus.CONFLICT,
+        ),
+      );
     }
     this._status = 'FAILED';
     this._callbackData = callbackData;
@@ -113,6 +127,7 @@ export class PaymentEntity extends AggregateRoot<string> {
     this.addDomainEvent(
       new PaymentFailedEvent(this.id, this._userId, this._provider),
     );
+    return Result.ok(undefined);
   }
 
   /** Emit completed event without modifying state (used when DB was already updated atomically). */
@@ -129,11 +144,18 @@ export class PaymentEntity extends AggregateRoot<string> {
     );
   }
 
-  markRefunded(): void {
+  markRefunded(): Result<void, DomainException> {
     if (this._status !== 'COMPLETED') {
-      throw new Error('Chỉ có thể hoàn tiền cho thanh toán đã hoàn tất');
+      return Result.err(
+        new DomainException(
+          ErrorCode.PAYMENT_ALREADY_PROCESSED,
+          'Chỉ có thể hoàn tiền cho thanh toán đã hoàn tất',
+          HttpStatus.CONFLICT,
+        ),
+      );
     }
     this._status = 'REFUNDED';
     this.updatedAt = new Date();
+    return Result.ok(undefined);
   }
 }