feat: full wagon cancel, leg board, wagon dates

feat(freight): editable train leg times, SL invoice payer

apps/edr-freight-web/backoffice/src/services/wagon.service.ts

@@ -26,6 +26,9 @@ export interface Wagon {
     lengthMeters?: number;
   } | null;
   status: Freight.WagonStatus;
+  /** Latest status-log flip to MAINTENANCE / to AVAILABLE (list endpoint only). */
+  lastMaintenanceAt?: string | null;
+  lastAvailableAt?: string | null;
   currentYardId: string | null;
   currentYard?: { id: string; label?: string; code?: string } | null;
   /** Odd EXPORT run (Ethiopia → Djibouti); null when the wagon is not on a run. */