feat(intercity): raise a GRN when a facility loads or unloads cargo

Every facility raises a GRN — the goods changed hands, whether or not anyone
stores them. What differs is what happens next: Indode has a warehouse, so cargo
left there goes through the existing warehouse flow and accrues storage and
demurrage; Sebeta, Modjo, Adama and Dire Dawa only move cargo between train and
truck, so the handling event and its GRN are the whole record.

facility_handling_events carries that record because warehouse_inventory cannot:
its warehouse/yard/zone are NOT NULL, so a facility with equipment but no
warehouse could never have a row there. inventory_id links the storage record
when the facility does keep the cargo, which is what ties an Indode handover to
its demurrage.

generateGrnNumber moves to common/grn.util.ts so a GRN raised at a facility is
indistinguishable from one raised in a warehouse — the two live in different
tables, and a second generator would let the formats drift.

Recording is best-effort: the cargo moved regardless, so paperwork must never
fail the journey.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/edr-freight-api/src/modules/train-scheduling/train-scheduling.module.ts

@@ -7,6 +7,8 @@ import { BookingsModule } from '../bookings/bookings.module';
 import { Container } from '../container-management/entities/container.entity';
 import { LocomotivesModule } from '../locomotives/locomotives.module';
 import { RuleEngineModule } from '../rule-engine/rule-engine.module';
+import { FacilityHandlingService } from './facility-handling.service';
+import { FacilityHandlingEvent } from './entities/facility-handling-event.entity';
 import { Locomotive } from '../locomotives/entities/locomotive.entity';
 import { Route } from '../routes/entities/route.entity';
 import { TrainSetLocomotive } from '../train-sets/entities/train-set-locomotive.entity';
@@ -41,6 +43,7 @@ import { ContractsModule } from '../contracts/contracts.module';
 @Module({
   imports: [
     TypeOrmModule.forFeature([
+      FacilityHandlingEvent,
       Locomotive,
       WagonType,
       TrainSet,
@@ -81,6 +84,7 @@ import { ContractsModule } from '../contracts/contracts.module';
     BookingSplitService,
     IntercityService,
     BookingJourneyService,
+    FacilityHandlingService,
   ],
   exports: [
     TrainSchedulingService,