implement empty-container return service: add return quantity handling, update related DTOs, services, and UI components

apps/edr-freight-api/src/migrations/2270000000000-AddContainerReturnQuantity.ts

@@ -0,0 +1,27 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+
+/**
+ * Adds freight.booking_container.return_quantity — how many units of a
+ * container line ship with the empty-container-return service (≤ quantity).
+ * Mirrors hazardous_quantity / reefer_quantity: captured per line at booking
+ * creation when the contract enables WITH_RETURN (container freight only) and
+ * drives the booking-level equipment_return flag that fires the WITH_RETURN
+ * pricing surcharge.
+ */
+export class AddContainerReturnQuantity2270000000000
+  implements MigrationInterface
+{
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`
+      ALTER TABLE freight.booking_container
+        ADD COLUMN IF NOT EXISTS return_quantity SMALLINT NOT NULL DEFAULT 0;
+    `);
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`
+      ALTER TABLE freight.booking_container
+        DROP COLUMN IF EXISTS return_quantity;
+    `);
+  }
+}