feat(clientes): alta de cliente in one screen, opening balance as a payment

The 2026-10-08 ask: open an account without four screens — cliente,
propiedad, servicios and the saldo inicial, taken as the first payment.

POST /customers/onboard writes it all in one Prisma transaction; a bad
service or a taken folder number leaves nothing behind (rolled back on dev).
A cash opening balance goes through the EFE receipt book inside that same
transaction, so it gets its folio and its C<folio> credit; a check posts a
CHECK DEPOSIT against the number given. /clientes/alta pre-fills the next
free folder number and links the receipt for printing. The old
customer-only form stays as "Solo cliente".

Built without the screen sketch from the meeting (it never arrived); the
fields are the legacy ones.

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

apps/api/src/customers/customers.module.ts

@@ -1,11 +1,12 @@
 import { Module } from "@nestjs/common";
 import { SettingsModule } from "../settings/settings.module";
+import { CashReceiptsModule } from "../cash-receipts/cash-receipts.module";
 import { CustomersController } from "./customers.controller";
 import { CustomersService } from "./customers.service";
 import { NumidService } from "./numid.service";
 
 @Module({
-  imports: [SettingsModule],
+  imports: [SettingsModule, CashReceiptsModule],
   controllers: [CustomersController],
   providers: [CustomersService, NumidService],
   exports: [NumidService],