Add customers management module with database schema and validation

- Introduced `CustomersModule` to manage customer data, including read and write controllers.
- Created database migrations for the `customers` and `customer_contacts` tables, including constraints and unique indexes.
- Implemented validation for customer fields such as name, code, and address with corresponding utility functions.
- Developed service and repository layers for handling customer data operations.
- Added unit tests for the customers service, repository, and controllers to ensure functionality and correctness.
- Updated application module to include the new `CustomersModule` for better organization.

src/modules/configuration/customers/customers.module.ts

@@ -0,0 +1,12 @@
+import { Module } from '@nestjs/common';
+import { CustomersReadController } from './customers-read.controller';
+import { CustomersWriteController } from './customers-write.controller';
+import { CustomersRepository } from './customers.repository';
+import { CustomersService } from './customers.service';
+
+@Module({
+  controllers: [CustomersReadController, CustomersWriteController],
+  providers: [CustomersRepository, CustomersService],
+  exports: [CustomersService],
+})
+export class CustomersModule {}