feat(train-sets): implement multi-locomotive support for train sets

- Added TrainSetLocomotive entity to link multiple locomotives to a train set.
- Updated TrainSet entity to include a OneToMany relationship with TrainSetLocomotive.
- Modified the train scheduling logic to require at least two locomotives for a train set.
- Enhanced the UI components to support selecting multiple locomotives.
- Introduced new permissions for viewing customs clearance.
- Updated migrations to create the train_set_locomotives table and backfill existing data.
- Implemented utility functions for managing train numbers based on cargo type and direction.
- Added tests for train number utilities to ensure correct functionality.

apps/edr-freight-api/src/modules/train-scheduling/dto/create-container-train-schedule.dto.ts

@@ -1,6 +1,15 @@
 import { ApiProperty, ApiPropertyOptional } from '@nestjs/swagger';
 import { Type } from 'class-transformer';
-import { IsDateString, IsInt, IsNumber, IsOptional, IsUUID, Min } from 'class-validator';
+import {
+  ArrayMinSize,
+  IsArray,
+  IsDateString,
+  IsInt,
+  IsNumber,
+  IsOptional,
+  IsUUID,
+  Min,
+} from 'class-validator';
 
 export class CreateContainerTrainScheduleDto {
   @ApiProperty({ format: 'uuid' })
@@ -11,9 +20,15 @@ export class CreateContainerTrainScheduleDto {
   @IsDateString()
   scheduleDate!: string;
 
-  @ApiProperty({ format: 'uuid' })
-  @IsUUID()
-  locomotiveId!: string;
+  @ApiProperty({
+    type: [String],
+    format: 'uuid',
+    description: 'Locomotives pulling the train (minimum 2 — front and back)',
+  })
+  @IsArray()
+  @ArrayMinSize(2, { message: 'A train must be pulled by at least two locomotives' })
+  @IsUUID('all', { each: true })
+  locomotiveIds!: string[];
 
   @ApiPropertyOptional({ description: 'Maximum total booking weight allowed on this train' })
   @IsOptional()