feat(appointments): expose destination warehouse options

lastleg-service/src/main/java/com/baiyue/lastleg/appointmentplanning/AppointmentCargoService.java

@@ -35,6 +35,11 @@ public class AppointmentCargoService {
         return new PageResult<>(rows, page, size, total, (total + size - 1) / size);
     }
 
+    /** 查询下拉框与货物分页共用权威目录范围，不从当前页猜测目的仓。 */
+    public List<String> destinations() {
+        return scope().destinations().stream().distinct().sorted().toList();
+    }
+
     private record Scope(List<String> origins, List<String> destinations) { }
     private Scope scope() {
         final List<AppointmentWarehouseClient.Warehouse> catalog;