feat(favorites): keep customer favourites on the server, as legacy did (FAV-01)

Both apps kept favourites in memory only, and the API had no route, so
the 874 favourites imported from legacy major_favorites never showed.

- GET customer/me/favorites, POST customer/me/favorites/toggle
- apps load them on sign-in, clear on sign-out, toggle optimistically
  and roll back on failure

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/api/src/app.module.ts

@@ -5,6 +5,7 @@ import { CustomersModule } from './modules/customers/customers.module';
 import { CustomerAuthModule } from './modules/customer-auth/customer-auth.module';
 import { SalesExpertAppModule } from './modules/sales-expert-app/sales-expert-app.module';
 import { CustomerProfileModule } from './modules/customer-profile/customer-profile.module';
+import { CustomerFavoritesModule } from './modules/customer-favorites/customer-favorites.module';
 import { CustomerReportModule } from './modules/customer-report/customer-report.module';
 import { SmsModule } from './modules/sms/sms.module';
 import { OrdersModule } from './modules/orders/orders.module';
@@ -63,6 +64,7 @@ import { SalesAgentModule } from './modules/sales-agent/sales-agent.module';
     CustomerAuthModule,
     SalesExpertAppModule,
     CustomerProfileModule,
+    CustomerFavoritesModule,
     CustomerReportModule,
     SalesAgentModule,
     OrdersModule,