feat: add AirShelf core implementation

core/backend/apps/ops/urls.py

@@ -0,0 +1,9 @@
+from rest_framework.routers import DefaultRouter
+
+from .views import NotificationViewSet
+
+
+router = DefaultRouter()
+router.register("notifications", NotificationViewSet, basename="notification")
+
+urlpatterns = router.urls