feat: dodaj dodatne troškove s OCR sinkronizacijom

Dodana je tablica DODATNI TROŠKOVI za putni nalog (backend model + API +
frontend modal) s izračunom ukupnog iznosa za isplatu.

Upload računa sada odmah upisuje redak u dodatne troškove, a asinkroni OCR
(Celery) naknadno pokušava popuniti broj računa i iznos iz slike/PDF-a.

Uvedena je invalidacija PDF cache-a nakon promjena računa/dodatnih troškova
kako bi generirani PDF uvijek prikazivao najnovije podatke.

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

backend/modules/fleet/tests/test_work_order_images_endpoint.py

@@ -2,12 +2,14 @@ from django.contrib.auth import get_user_model
 from django.core.files.uploadedfile import SimpleUploadedFile
 from django.test import TestCase
 from django.urls import reverse
+from django.utils import timezone
 from rest_framework.test import APIClient
 import uuid
 from io import BytesIO
+from datetime import timedelta
 from PIL import Image
 
-from modules.fleet.models import Vehicle, WorkOrder, WorkOrderInvoice, VehicleServiceRecord, VehicleServicePhoto
+from modules.fleet.models import Vehicle, WorkOrder, WorkOrderInvoice, VehicleServiceRecord, VehicleServicePhoto, GeneratedWorkOrderPdf
 
 
 def create_test_image(filename='test.jpg', size=(40, 40), color='red'):
@@ -167,3 +169,74 @@ class WorkOrderImagesEndpointTests(TestCase):
         file_response = self.client.get(image_url)
         self.assertEqual(file_response.status_code, 200)
         self.assertEqual(file_response['Content-Type'], 'application/pdf')
+
+    def test_additional_costs_table_can_be_saved_and_total_is_computed(self):
+        url = f"/api/fleet/work-orders/{self.work_order.pk}/additional-costs-table/"
+        response = self.client.put(
+            url,
+            data={
+                "rows": [
+                    {"naziv": "Cestarina", "broj_racuna": "R-100", "ukupan_iznos": "12,50", "prilog": "racun-1.pdf"},
+                    {"naziv": "Gorivo", "broj_racuna": "R-101", "ukupan_iznos": "7.50", "prilog": "racun-2.jpg"},
+                ]
+            },
+            format='json',
+        )
+        self.assertEqual(response.status_code, 200, response.content)
+        payload = response.json()
+        self.assertEqual(payload.get('total_for_payout'), '20.00')
+        rows = payload.get('data', {}).get('rows', [])
+        self.assertEqual(len(rows), 2)
+
+    def test_task_service_context_contains_additional_costs_table(self):
+        table_url = f"/api/fleet/work-orders/{self.work_order.pk}/additional-costs-table/"
+        save_response = self.client.put(
+            table_url,
+            data={"rows": [{"naziv": "Parking", "broj_racuna": "P-1", "ukupan_iznos": "5.00", "prilog": "parking.pdf"}]},
+            format='json',
+        )
+        self.assertEqual(save_response.status_code, 200, save_response.content)
+
+        context_response = self.client.get(f"/api/fleet/work-orders/{self.work_order.pk}/task-service-context/")
+        self.assertEqual(context_response.status_code, 200, context_response.content)
+        payload = context_response.json()
+        self.assertIn('additional_costs_table', payload)
+        self.assertEqual(payload['additional_costs_table']['total_for_payout'], '5.00')
+
+    def test_invoice_upload_immediately_appears_in_additional_costs_table(self):
+        create_response = self.client.post(
+            reverse('work-order-invoice-list'),
+            data={
+                'work_order': str(self.work_order.pk),
+                'naziv_racuna': 'Test2',
+                'datum': '2026-07-19',
+                'image': create_test_image('test2.jpg'),
+            },
+            format='multipart',
+        )
+        self.assertEqual(create_response.status_code, 201, create_response.content)
+
+        table_response = self.client.get(f"/api/fleet/work-orders/{self.work_order.pk}/additional-costs-table/")
+        self.assertEqual(table_response.status_code, 200, table_response.content)
+        rows = table_response.json().get('data', {}).get('rows', [])
+        self.assertEqual(len(rows), 1)
+        self.assertEqual(rows[0].get('naziv'), 'Test2')
+
+    def test_additional_costs_update_invalidates_work_order_pdf_cache(self):
+        cached = GeneratedWorkOrderPdf.objects.create(
+            work_order=self.work_order,
+            requested_by=self.user,
+            pdf_type='work_order',
+            status='ready',
+            filename='MT010101.work-order.pdf',
+            expires_at=timezone.now() + timedelta(hours=1),
+        )
+        response = self.client.put(
+            f"/api/fleet/work-orders/{self.work_order.pk}/additional-costs-table/",
+            data={"rows": [{"naziv": "Test", "broj_racuna": "R-1", "ukupan_iznos": "10.00", "prilog": "r1.pdf"}]},
+            format='json',
+        )
+        self.assertEqual(response.status_code, 200, response.content)
+        cached.refresh_from_db()
+        self.assertFalse(cached.is_active)
+        self.assertEqual(cached.status, 'failed')