fix: sync multi-day work hours accounting

Aggregate task work-hour rows into travel-cost calculations and monthly servicer reporting, and keep the frontend calendar aligned with the task work-hours source.

backend/modules/task_management/tests/test_serializers.py

@@ -2,7 +2,7 @@ from django.test import TestCase
 from modules.task_management.serializers import TaskSerializer
 from rest_framework.exceptions import ValidationError
 from django.contrib.auth import get_user_model
-from modules.task_management.models import Task
+from modules.task_management.models import Task, TaskWorkHoursTable
 from modules.fleet.models import Vehicle, WorkOrder
 from modules.crm.models import Client
 
@@ -86,6 +86,22 @@ class TaskSerializerTests(TestCase):
         assert serializer.data['vehicle_owner_name'] == 'Klijent zadatka'
         assert serializer.data['vehicle_asset_type'] == 'crane'
 
+    def test_work_hours_table_is_included_in_serialized_output(self):
+        task = Task.objects.create(title="Task work hours", assigned_to=self.user, vehicle=self.vehicle)
+        TaskWorkHoursTable.objects.create(
+            task=task,
+            data={
+                'rows': [
+                    {'date': '12.07.2026', 'work_hours': '8', 'travel_hours': '2'},
+                ]
+            },
+        )
+
+        serializer = TaskSerializer(instance=task)
+        assert serializer.data['work_hours_table']['data']['rows'][0]['date'] == '12.07.2026'
+        assert serializer.data['work_hours_table']['data']['rows'][0]['work_hours'] == '8'
+        assert serializer.data['work_hours_table']['data']['rows'][0]['travel_hours'] == '2'
+
     def test_scheduled_date_accepts_valid_date(self):
         serializer = TaskSerializer(
             data={"title": "Task mit datum", "status": "aktivan",