P2-14: Deposit installment tracking + refund approval flow

- Add DepositInstallment entity (id, depositId, amount, dueDate, paidDate, status, createdAt)
- Add installments OneToMany relation to Deposit entity with cascade+eager
- Add refund approval fields: refundStatus, refundRequestedAt, refundApprovedBy, refundApprovedAt
- Add installment DTOs (CreateInstallmentDto, UpdateInstallmentDto)
- Add refund approval DTOs (ApproveRefundDto, CreateDepositWithInstallmentsDto)
- Service: add/create/update/delete installments, requestRefund, approveRefund, findPendingRefunds
- Controller: GET deposits/:id, GET pending-refunds, POST :id/installments, PUT installments/:id, DELETE installments/:id, POST :id/request-refund, PUT :id/approve-refund
- Frontend: detail modal with installment list, refund request button, pending refunds tab with approve actions

apps/server/src/deposits/deposits.module.ts

@@ -1,12 +1,13 @@
 import { Module } from '@nestjs/common';
 import { TypeOrmModule } from '@nestjs/typeorm';
 import { Deposit } from '../entities/deposit.entity';
+import { DepositInstallment } from '../entities/deposit-installment.entity';
 import { DepositsService } from './deposits.service';
 import { DepositsController } from './deposits.controller';
 import { OperationLogsModule } from '../operation-logs/operation-logs.module';
 
 @Module({
-  imports: [TypeOrmModule.forFeature([Deposit]), OperationLogsModule],
+  imports: [TypeOrmModule.forFeature([Deposit, DepositInstallment]), OperationLogsModule],
   controllers: [DepositsController],
   providers: [DepositsService],
   exports: [DepositsService],