fix(operations): last-mile assign until load fully trucked + 40ft cap

Assign was gated on any truck assigned, blocking multi-truck
deliveries. Gate on remaining containers (or bulk tonnage) instead, show
covered/total in the modal, cap a 40ft container to one truck with no
size mixing (mirrors assertTruckLoad), and lock arrived/departed rows.

apps/edr-freight-api/src/migrations/2900000000000-LivestockPerItem.ts

@@ -0,0 +1,28 @@
+import { MigrationInterface, QueryRunner } from "typeorm";
+
+/**
+ * Livestock is billed and counted per head, not per ton — line it up with the
+ * other break-bulk cargo types (Machinery, Truck, Automobile) so bulk
+ * storage/demurrage fees charge per item instead of per ton for it.
+ */
+export class LivestockPerItem2900000000000 implements MigrationInterface {
+  name = "LivestockPerItem2900000000000";
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`
+      UPDATE freight.cargo_types
+         SET unit_of_measure = 'PER_ITEM'
+       WHERE code = 'LIVESTOCK'
+         AND unit_of_measure IS DISTINCT FROM 'PER_ITEM'
+    `);
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`
+      UPDATE freight.cargo_types
+         SET unit_of_measure = 'PER_TON'
+       WHERE code = 'LIVESTOCK'
+         AND unit_of_measure IS DISTINCT FROM 'PER_TON'
+    `);
+  }
+}