Add train deactivation feature and import train number management

- Introduced DEACTIVATED status for trains, allowing staff to park trains indefinitely.
- Implemented methods to deactivate and reactivate trains in the TrainBuilderService.
- Added UI components for train deactivation and reactivation in TrainBuilderDetailPage.
- Created a dropdown setting for admin-managed import train numbers, with corresponding migrations.
- Updated yard code length to accommodate soft-delete suffix.
- Enhanced train status handling to include DEACTIVATED state.

packages/types/src/freight/index.ts

@@ -136,6 +136,8 @@ export enum TrainStatus {
   InService = "IN_SERVICE",
   UnderMaintenance = "UNDER_MAINTENANCE",
   OutOfService = "OUT_OF_SERVICE",
+  /** Parked indefinitely by staff; only allowed with no active schedule. */
+  Deactivated = "DEACTIVATED",
 }
 
 export enum CargoType {