feat: dodaj bilješke widget i admin kalendar/notifikacije

Uveden je novi Notes drawer s kalendar integracijom, zajednički DRY
left-slide mehanizam te međusobno isključivo prikazivanje s Kalendar
widgetom.

Backend i frontend su prošireni za servisne bilješke (uključujući slanje
na više servisera), dodan je users/servicers endpoint, te su uvedene
warning notifikacije kada serviser ima više od 2 zadatka isti dan.

U admin su dodane stavke za Bilješke i zaseban Kalendar zadataka (proxy
TaskCalendar) radi lakšeg operativnog pregleda.

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

backend/core/users/tests/test_users.py

@@ -58,4 +58,29 @@ class TestUserAPI:
         self.user.refresh_from_db()
         
         assert response.status_code == status.HTTP_200_OK
-        assert self.user.first_name == "Inženjer"
+        assert self.user.first_name == "Inženjer"
+
+    def test_get_servicers_returns_only_servicers(self):
+        serviser = User.objects.create_user(
+            email="serviser@test.hr",
+            first_name="Serviser",
+            last_name="Jedan",
+            password="strongpassword123",
+            is_serviser=True,
+            is_team_member=True,
+        )
+        non_serviser = User.objects.create_user(
+            email="nons@test.hr",
+            first_name="Nije",
+            last_name="Serviser",
+            password="strongpassword123",
+            is_serviser=False,
+            is_team_member=True,
+        )
+        self.client.force_authenticate(user=self.user)
+        url = reverse('user-servicers')
+        response = self.client.get(url)
+        assert response.status_code == status.HTTP_200_OK
+        returned_ids = {str(item['id']) for item in response.data}
+        assert str(serviser.id) in returned_ids
+        assert str(non_serviser.id) not in returned_ids

backend/core/users/views.py

@@ -30,6 +30,12 @@ class UserViewSet(viewsets.ModelViewSet):
         serializer = TeamMemberSerializer(queryset, many=True)
         return Response(serializer.data)
 
+    @action(detail=False, methods=['get'], url_path='servicers')
+    def servicers(self, request):
+        queryset = User.objects.filter(is_active=True, is_serviser=True).order_by('first_name', 'last_name', 'email')
+        serializer = TeamMemberSerializer(queryset, many=True)
+        return Response(serializer.data)
+
     def perform_update(self, serializer):
         # Delegiramo logiku servisu
         UserService.update_user_profile(