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/contract-notifier.service.ts

@@ -143,6 +143,19 @@ export class ContractNotifierService {
     this.inApp(c, 'Contract rejected', msg);
   }
 
+  /**
+   * A later approver sent the contract back to an earlier stage of the chain.
+   * Staff-only: the customer is not involved in an internal send-back — their
+   * contract simply stays "under approval".
+   */
+  sentBackToStep(c: Contract, targetRole: string, reason: string): void {
+    this.inAppStaff(
+      c,
+      'Contract returned in approval chain',
+      `Contract ${c.reference} was sent back to the ${targetRole} step. Reason: ${reason}`,
+    );
+  }
+
   /** Staff requested changes before approval. */
   changesRequested(c: Contract, note: string): void {
     const msg =