feat: complete cmpp platform phases 0-5

api/src/billing/billing.module.ts

@@ -0,0 +1,10 @@
+import { Module } from '@nestjs/common';
+import { BillingController, ClientBillingController } from './billing.controller';
+import { BillingService } from './billing.service';
+
+@Module({
+  controllers: [BillingController, ClientBillingController],
+  providers: [BillingService],
+  exports: [BillingService],
+})
+export class BillingModule {}