Add freight demo data seeder and permissions management

- Introduced `DemoFreightDataSeeder` to seed demo freight data including wagons, approval rules, and staff users.
- Added `seed:freight-demo` script to `package.json` for easy execution.
- Updated permissions for operations officer and added permission checks in various components.
- Enhanced sidebar and booking actions to respect user permissions.

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

@@ -96,7 +96,8 @@ export class TrainSchedulingController {
   }
 
   @Get("bookable-schedules")
-  // @TrainSchedulingView()
+  // No staff guard: customers hit this while creating a booking to find OPEN
+  // same-route schedules. Do not attach train_scheduling permissions here.
   @ApiOperation({
     summary: "OPEN same-route schedules a new booking can target",
   })