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/models.py

@@ -45,6 +45,15 @@ def _work_order_invoice_upload_to(instance, filename):
     unique_name = f"{uuid.uuid4().hex}_{filename}"
     return f"fleet/{vehicle_reg}/work_order_invoices/{unique_name}"
 
+def _work_order_photo_upload_to(instance, filename):
+    vehicle_reg = 'unknown'
+    try:
+        vehicle_reg = instance.work_order.vehicle.registration_number
+    except Exception:
+        vehicle_reg = 'unknown'
+    unique_name = f"{uuid.uuid4().hex}_{filename}"
+    return f"fleet/{vehicle_reg}/work_order_photos/{unique_name}"
+
 
 class VehicleServicePhoto(BaseModel):
     """
@@ -344,6 +353,37 @@ class WorkOrderInvoice(BaseModel):
         return f"{self.naziv_racuna} ({self.work_order_id})"
 
 
+class WorkOrderPhoto(BaseModel):
+    work_order = models.ForeignKey(
+        WorkOrder,
+        on_delete=models.CASCADE,
+        related_name='photos',
+        verbose_name=_("Putni nalog"),
+    )
+    image = models.ImageField(
+        upload_to=_work_order_photo_upload_to,
+        verbose_name=_("Fotografija putnog naloga"),
+    )
+    description = models.CharField(max_length=255, blank=True, verbose_name=_("Opis"))
+    uploaded_by = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        null=True,
+        blank=True,
+        on_delete=models.SET_NULL,
+        related_name='uploaded_work_order_photos',
+        verbose_name=_("Postavio"),
+    )
+    is_active = models.BooleanField(default=True, verbose_name=_("Aktivan"))
+
+    class Meta:
+        verbose_name = _("Fotografija putnog naloga")
+        verbose_name_plural = _("Fotografije putnog naloga")
+        ordering = ['-created_at']
+
+    def __str__(self):
+        return f"WorkOrderPhoto {self.pk} ({self.work_order_id})"
+
+
 class VehicleServiceRecord(BaseModel):
     """
     Zapisi o servisima/popravcima na vozilu.