add yard distances management to rule engine

- Introduced new yard distances resource with CRUD operations.
- Created migration for yard distances table with necessary constraints.
- Implemented service and repository for yard distances handling.
- Added controller for API endpoints to manage yard distances.
- Updated rule engine configuration to include yard distances.
- Enhanced rule engine resource page to support yard distance selection.
- Updated contracts and train builder pages to handle new yard distance logic.
- Added error handling utility for better error message extraction.

apps/edr-freight-api/src/modules/contracts/dto/approve-step.dto.ts

@@ -1,5 +1,5 @@
 import { ApiProperty, ApiPropertyOptional } from '@nestjs/swagger';
-import { IsOptional, IsString, MinLength } from 'class-validator';
+import { IsOptional, IsString, IsUUID, MinLength } from 'class-validator';
 
 export class ApproveStepDto {
   @ApiProperty({ description: 'LINE_STAFF | DIRECTOR | CEO' })
@@ -26,6 +26,22 @@ export class RejectStepDto {
   @IsString()
   @MinLength(1)
   reason!: string;
+
+  /**
+   * Where the rejection lands. Omitted → the customer: the contract goes to
+   * REJECTED and the customer must resubmit (unchanged legacy behaviour, and
+   * the only option for the first approver in the chain). Set to an EARLIER
+   * approved step's id → send-back: that step and everything after it reset to
+   * PENDING and the chain re-runs from there; the contract never leaves
+   * PENDING_APPROVAL and the customer is not involved.
+   */
+  @ApiPropertyOptional({
+    description:
+      'Id of an earlier approval step to send the contract back to. Omit to reject to the customer.',
+  })
+  @IsOptional()
+  @IsUUID()
+  returnToStepId?: string;
 }
 
 export class CancelContractDto {