feat: implement 20ft container weight-pairing validation

- Added ContainerValidationService to handle 20ft weight-pairing logic.
- Introduced validate20ftWeightPairing utility function to check weight differences.
- Updated BookingPricingService to include overweight line details and pairing errors in price response.
- Enhanced BookingTransitionService to reject submissions with unpairable 20ft containers.
- Created ShipmentValidation interface for pre-submit validation of container contracts.
- Integrated shipment validation into the contract booking process, providing warnings for overweight containers and hard blocks for pairing errors.
- Updated front-end components to display validation results and prevent submission when errors are present.

apps/edr-freight-api/src/modules/bookings/booking-transition.service.ts

@@ -16,6 +16,7 @@ import { FilesService } from '../files/files.service';
 import { FileUploadSettingsService } from '../file-upload-settings/file-upload-settings.service';
 import { BookingContractService } from './booking-contract.service';
 import { BookingPricingService } from './booking-pricing.service';
+import { ContainerValidationService } from './container-validation.service';
 import { BookingsRepository } from './bookings.repository';
 import { assertBookingStatus } from './booking-status.util';
 import { clearanceCodesForBooking } from './clearance.util';
@@ -51,6 +52,7 @@ export class BookingTransitionService {
     @Inject(forwardRef(() => ClearanceWorkflowService))
     private readonly workflowService: ClearanceWorkflowService,
         private readonly invoiceService: BookingInvoiceService,
+    private readonly containerValidationService: ContainerValidationService,
 
   ) {}
 
@@ -58,6 +60,19 @@ export class BookingTransitionService {
     return this.bookingClearanceService.isPhasedGeneralCustomsBooking(booking);
   }
 
+  /** Reject submit when the booking's 20ft containers can't be balanced onto wagons. */
+  private async assert20ftPairable(booking: Booking): Promise<void> {
+    const violations =
+      await this.containerValidationService.validate20ftPairing(booking);
+    if (violations.length) {
+      throw new BadRequestException(
+        `Cannot submit — 20ft containers cannot be paired on wagons: ${violations
+          .map((v) => v.message)
+          .join(' ')}`,
+      );
+    }
+  }
+
   async submit(bookingId: string): Promise<SubmitBookingResponseDto> {
     const booking = await this.bookingsService.findById(bookingId);
     assertBookingStatus(booking, ["DRAFT", "CHANGES_REQUESTED"]);
@@ -78,6 +93,11 @@ export class BookingTransitionService {
       requiresDirectorApproval: false,
     });
 
+    // 20ft weight-pairing hard block: two 20ft on a wagon must differ ≤ the cap.
+    // If no balanced pairing exists the booking cannot proceed (overweight only
+    // warns; this rejects). An odd leftover 20ft is fine — it goes to consolidation.
+    await this.assert20ftPairable(booking);
+
     const stored = booking.pricingBreakdown as {
       lineItems?: PriceLineItemDto[];
       totalAmount?: number;
@@ -158,6 +178,7 @@ export class BookingTransitionService {
       hardBlocked: computed.hardBlocked,
       requiresDirectorApproval: false,
     });
+    await this.assert20ftPairable(booking);
 
     await this.pricingService.createPricingSnapshots(
       bookingId,