feat(warehouse,last-mile): truck load size rule, dedup last-mile, driver-required + arrival prefill

Truck loading:
- loadTruck enforces max 2 containers / one 40ft (two 20ft) and auto-marks an
  assigned truck arrived on load; container-items payload + modal expose
  container size with a client-side selection cap.
- Show "#x containers pending assignment" in the portal truck card and the
  backoffice container modal.

Last-mile:
- create() is idempotent — return the existing record for a booking instead of
  inserting a duplicate delivery row (fixed the same booking showing twice in
  Assign-Mile).
- setVehicles/update reject a truck with no assigned driver; the Assign toast
  now surfaces the reason.
- New GET /last-mile/booking/:id/arrival-trucks returns assigned EDR trucks with
  driver details; ReleaseOrderModal fetches and auto-fills them so an assigned
  EDR truck no longer reads as "not assigned yet".

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

apps/edr-freight-api/src/modules/bookings/dto/load-customer-truck.dto.ts

@@ -1,9 +1,11 @@
-import { ArrayMinSize, ArrayUnique, IsArray, Matches } from 'class-validator';
+import { ArrayMaxSize, ArrayMinSize, ArrayUnique, IsArray, Matches } from 'class-validator';
 
 /** Containers loaded onto a truck at Truck_dispatch (after arrival, before it leaves). */
 export class LoadCustomerTruckDto {
   @IsArray()
   @ArrayMinSize(1)
+  // A truck carries at most 2 containers (two 20ft, or one 40ft).
+  @ArrayMaxSize(2)
   @ArrayUnique()
   @Matches(/^[A-Z]{4}\d{7}$/, {
     each: true,