feat: add async monthly ZIP generation with notifications

Implement background generation for monthly SN/PN ZIP archives and expose completion through in-app notifications.

- add GeneratedFleetArchive persistence model with expiry metadata
- add archive request/download endpoints and Celery background tasks
- emit notification stages for requested/completed/failed archive jobs
- update calendar bulk download actions to trigger async requests
- add notification modal actions to download generated ZIP files
- extend backend tests for async archive request and download flows

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

backend/modules/fleet/tests/test_work_order_images_endpoint.py

@@ -8,12 +8,20 @@ import uuid
 from io import BytesIO
 from datetime import date, timedelta
 import zipfile
-from pathlib import Path
-from django.conf import settings
 from PIL import Image
 
-from modules.fleet.models import Vehicle, WorkOrder, WorkOrderInvoice, VehicleServiceRecord, VehicleServicePhoto, GeneratedWorkOrderPdf
+from modules.fleet.models import (
+    Vehicle,
+    WorkOrder,
+    WorkOrderInvoice,
+    VehicleServiceRecord,
+    VehicleServicePhoto,
+    GeneratedWorkOrderPdf,
+    GeneratedFleetArchive,
+    VehicleNotification,
+)
 from modules.task_management.models import Task
+from modules.fleet.tasks import build_monthly_archive_cached_task
 
 
 def create_test_image(filename='test.jpg', size=(40, 40), color='red'):
@@ -310,8 +318,6 @@ class WorkOrderImagesEndpointTests(TestCase):
             image=create_test_pdf('racun-prosinac.pdf'),
             created_by=self.user,
         )
-
-        before_files = set((Path(settings.MEDIA_ROOT) / 'fleet' / 'generated_archives').glob('*.zip'))
         response = self.client.get('/api/fleet/reports/monthly-work-orders-archive/?year=2033&month=12')
         self.assertEqual(response.status_code, 200, response.content)
         self.assertEqual(response['Content-Type'], 'application/zip')
@@ -321,7 +327,83 @@ class WorkOrderImagesEndpointTests(TestCase):
         self.assertIn('MT150726.work-order.pdf', names)
         self.assertTrue(any(name.startswith('Racuni/MT150726/') for name in names), names)
 
-        generated_archives_dir = Path(settings.MEDIA_ROOT) / 'fleet' / 'generated_archives'
-        self.assertTrue(generated_archives_dir.exists())
-        after_files = set(generated_archives_dir.glob('*.zip'))
-        self.assertTrue(after_files - before_files)
+    def test_monthly_service_tasks_archive_request_creates_ready_download_with_notification(self):
+        response = self.client.post(
+            '/api/fleet/reports/monthly-service-tasks-archive-request/',
+            data={'year': 2033, 'month': 12},
+            format='json',
+        )
+        self.assertIn(response.status_code, [200, 202], response.content)
+        payload = response.json()
+        self.assertIn('generated_archive_id', payload)
+
+        generated = GeneratedFleetArchive.objects.filter(
+            pk=payload['generated_archive_id'],
+            requested_by=self.user,
+            archive_type='service_tasks',
+        ).first()
+        self.assertIsNotNone(generated)
+        if generated.status != 'ready':
+            build_monthly_archive_cached_task.apply(args=[str(generated.pk)]).get()
+            generated.refresh_from_db()
+        self.assertEqual(generated.status, 'ready')
+
+        download_response = self.client.get(f"/api/fleet/reports/generated-archives/{generated.pk}/download/")
+        self.assertEqual(download_response.status_code, 200)
+        self.assertEqual(download_response['Content-Type'], 'application/zip')
+        archive_bytes = b''.join(download_response.streaming_content)
+
+        archive = zipfile.ZipFile(BytesIO(archive_bytes))
+        self.assertIn('MT150726.SN-Test_servisni_zadatak.docx', archive.namelist())
+
+        notifications = VehicleNotification.objects.filter(recipient=self.user).order_by('created_at')
+        self.assertTrue(notifications.filter(metadata__entity_type='fleet_archive', metadata__stage='requested').exists())
+        self.assertTrue(notifications.filter(metadata__entity_type='fleet_archive', metadata__stage='completed').exists())
+
+    def test_monthly_work_orders_archive_request_creates_ready_download_with_notification(self):
+        WorkOrderInvoice.objects.create(
+            work_order=self.work_order,
+            naziv_racuna='Prosinac račun',
+            datum='2033-12-10',
+            image=create_test_pdf('racun-prosinac.pdf'),
+            created_by=self.user,
+        )
+
+        response = self.client.post(
+            '/api/fleet/reports/monthly-work-orders-archive-request/',
+            data={'year': 2033, 'month': 12},
+            format='json',
+        )
+        self.assertIn(response.status_code, [200, 202], response.content)
+        payload = response.json()
+        self.assertIn('generated_archive_id', payload)
+
+        generated = GeneratedFleetArchive.objects.filter(
+            pk=payload['generated_archive_id'],
+            requested_by=self.user,
+            archive_type='work_orders',
+        ).first()
+        self.assertIsNotNone(generated)
+        if generated.status != 'ready':
+            build_monthly_archive_cached_task.apply(args=[str(generated.pk)]).get()
+            generated.refresh_from_db()
+        self.assertEqual(generated.status, 'ready')
+
+        download_response = self.client.get(f"/api/fleet/reports/generated-archives/{generated.pk}/download/")
+        self.assertEqual(download_response.status_code, 200)
+        self.assertEqual(download_response['Content-Type'], 'application/zip')
+        archive_bytes = b''.join(download_response.streaming_content)
+
+        archive = zipfile.ZipFile(BytesIO(archive_bytes))
+        names = archive.namelist()
+        self.assertIn('MT150726.work-order.pdf', names)
+        self.assertTrue(any(name.startswith('Racuni/MT150726/') for name in names), names)
+
+        self.assertTrue(
+            VehicleNotification.objects.filter(
+                recipient=self.user,
+                metadata__entity_type='fleet_archive',
+                metadata__archive_type='work_orders',
+                metadata__stage='completed',
+            ).exists()
+        )