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/modules/fleet/urls.py

@@ -2,7 +2,7 @@ from rest_framework.routers import DefaultRouter
 from django.urls import path
 from .views import (
     CraneViewSet, VehicleViewSet, WorkOrderViewSet, VehicleServiceRecordViewSet,
-    WorkOrderInvoiceViewSet, VehicleNotificationViewSet, VehicleServicePhotoViewSet, VehicleServiceAttachmentViewSet, pusher_auth,
+    WorkOrderInvoiceViewSet, ServiceContextNoteViewSet, VehicleNotificationViewSet, VehicleServicePhotoViewSet, VehicleServiceAttachmentViewSet, pusher_auth,
 )
 
 router = DefaultRouter()
@@ -10,6 +10,7 @@ router.register(r'vehicles', VehicleViewSet, basename='vehicle')
 router.register(r'cranes', CraneViewSet, basename='crane')
 router.register(r'work-orders', WorkOrderViewSet, basename='workorder')
 router.register(r'work-order-invoices', WorkOrderInvoiceViewSet, basename='work-order-invoice')
+router.register(r'service-notes', ServiceContextNoteViewSet, basename='service-context-note')
 router.register(r'service-records', VehicleServiceRecordViewSet, basename='service-record')
 router.register(r'notifications', VehicleNotificationViewSet, basename='vehicle-notification')
 router.register(r'service-photos', VehicleServicePhotoViewSet, basename='service-photo')