feat: WorkOrderPhoto izolacija, upload modal i SN stupac u tablici putnih naloga

- Dodan WorkOrderPhoto model (FK na WorkOrder, odvojen od VehicleServicePhoto)
- Migracija 0022_workorderphoto
- WorkOrderViewSet.images action refaktoriran: GET/POST koristi WorkOrderPhoto
- WorkOrderPhotoSerializer dodan u serializers.py
- WorkOrderPhotoInline dodan u admin.py
- Novi WorkOrderPhotoUpload.jsx modal s podrskom za onBack prop i z-[60]
- WorkOrderDetailModal: gumb Dodaj fotografije u editMode, photoUploadOpen state,
  ispravljen onSuccess callback (map na URL stringove), reset pri zatvaranju
- FleetDashboardShell: stupac SN u tablici putnih naloga (craneInfo.crane_serial_number)
- fleetDashboardStore: uklonjen dupli toast iz uploadWorkOrderPhoto
- Dodan test test_work_order_images_endpoint.py

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

backend/modules/fleet/serializers.py

@@ -5,6 +5,7 @@ from .models import (
     Vehicle,
     VehicleNotification,
     WorkOrder,
+    WorkOrderPhoto,
     WorkOrderInvoice,
     VehicleServiceRecord,
     VehicleServicePhoto,
@@ -198,6 +199,16 @@ class WorkOrderInvoiceSerializer(serializers.ModelSerializer):
         read_only_fields = ['id', 'created_by', 'created_at']
 
 
+class WorkOrderPhotoSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = WorkOrderPhoto
+        fields = ['id', 'work_order', 'image', 'description', 'uploaded_by', 'created_at']
+        read_only_fields = ['id', 'uploaded_by', 'created_at']
+        extra_kwargs = {
+            'work_order': {'required': False},
+        }
+
+
 class VehicleServiceRecordSerializer(serializers.ModelSerializer):
     crane = serializers.SerializerMethodField()
     crane_registration = serializers.SerializerMethodField()