Fix customer_truck_containers status

apps/edr-freight-api/src/modules/bookings/entities/customer-truck-container.entity.ts

@@ -23,4 +23,12 @@ export class CustomerTruckContainer extends BaseEntity {
 
   @Column({ name: 'container_number', type: 'varchar', length: 64 })
   containerNumber!: string;
+
+  /**
+   * When the container was actually loaded onto the truck by the operator.
+   * Null = customer-assigned (planned) but not yet loaded. Stage LOADED requires
+   * this to be set, so customer assignment alone does not mark a container loaded.
+   */
+  @Column({ name: 'loaded_at', type: 'timestamptz', nullable: true })
+  loadedAt?: Date | null;
 }