fix(warehouses): truck-arrival crash on duplicate containers; auto-GRN on import unload

Truck Arrival died with "[@mantine/core] Duplicate options are not supported"
when a booking carried the same container number on two container lines (the
unit uniqueness is per line, not per booking):
- bookingContainerWeights now GROUPs BY container number (MAX weight)
- the weighing modal dedupes both the containers MultiSelect and the
  assigned-trucks Select defensively, so bad data degrades instead of
  crashing the whole page

Import GRN is now issued automatically when the arrived train is unloaded:
autoUnloadArrivedBookings stamps GRN-IMPORT-<date>-<booking> on both the
create and update paths (never overwrites an existing GRN). The per-row GRN
button in the import queue lights up with no extra clicks.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/edr-freight-api/src/modules/warehouses/warehouse-inventory.service.ts

@@ -1597,6 +1597,8 @@ export class WarehouseInventoryService {
             status: 'UNLOADED',
             unloadedAt: now,
             arrivedAt: existing.arrivedAt ?? now,
+            // Import GRN is issued automatically at train unload.
+            ...(existing.grnNumber ? {} : { grnNumber: this.generateGrnNumber('IMPORT', booking.id, now) }),
           });
           await this.activityLog.record({
             activityType: 'INVENTORY_UNLOADED',
@@ -1630,6 +1632,7 @@ export class WarehouseInventoryService {
           quantity: 1,
           weight: Number(booking.weight) || 0,
           status: 'UNLOADED',
+          grnNumber: this.generateGrnNumber('IMPORT', booking.id, now),
           arrivedAt: now,
           unloadedAt: now,
           notes: allocated?.rule ? `Unloaded → ${allocated.path}` : 'Unloaded from arrived import train',
@@ -2757,11 +2760,12 @@ export class WarehouseInventoryService {
     const rows: Array<{ containerNumber: string; weightTons: string }> =
       await this.dataSource.query(
         `SELECT bcu.container_number AS "containerNumber",
-                COALESCE(bcu.vgm_tons, 0) AS "weightTons"
+                MAX(COALESCE(bcu.vgm_tons, 0)) AS "weightTons"
            FROM freight.booking_container_units bcu
            JOIN freight.booking_container bc
              ON bc.id = bcu.booking_container_id AND bc.deleted_at IS NULL
           WHERE bc.booking_id = $1 AND bcu.deleted_at IS NULL
+          GROUP BY bcu.container_number
           ORDER BY bcu.container_number`,
         [bookingId],
       );