feat: complete maintenance tracking backend

Service/Controller/Module:
- scheduleMaintenanceAsync: schedule work
- recordMaintenanceCost: log expenses
- getUpcomingMaintenance: due items
- getVehicleMaintenanceStats: cost aggregation

Endpoints:
- POST /maintenance/schedules
- POST /maintenance/costs
- PATCH /maintenance/schedules/:id
- GET /maintenance/upcoming/:vehicleId
- GET /maintenance/history/:vehicleId
- GET /maintenance/stats/:vehicleId

Migration: idempotent maintenance tables creation

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

apps/edr-freight-api/src/app.module.ts

@@ -70,6 +70,7 @@ import { OverviewModule } from './modules/overview/overview.module';
 import { VehiclesModule } from './modules/vehicles/vehicles.module';
 import { DriversModule } from './modules/drivers/drivers.module';
 import { FuelModule } from './modules/fuel/fuel.module';
+import { MaintenanceModule } from './modules/maintenance/maintenance.module';
 import { FirstMileModule } from './modules/first-mile/first-mile.module';
 import { LastMileModule } from './modules/last-mile/last-mile.module';
 import { InterchangeDocumentsModule } from './modules/interchange-documents/interchange-documents.module';
@@ -135,6 +136,7 @@ import { ImportOperationsModule } from './modules/import-operations/import-opera
     VehiclesModule,
     DriversModule,
     FuelModule,
+    MaintenanceModule,
     FirstMileModule,
     LastMileModule,
     InterchangeDocumentsModule,