Add settings page and configurable network map types.

Let users define sector/circle labels and geometry per map type, choose a type when creating maps, and sync types through local backup and API migrations.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/api/v1/urls.py

@@ -7,6 +7,7 @@ router = DefaultRouter()
 router.register('contacts', contact_views.ContactViewSet)
 router.register('relations', contact_views.RelationViewSet)
 router.register('network-maps', contact_views.NetworkMapViewSet)
+router.register('network-map-types', contact_views.NetworkMapTypeViewSet)
 
 urlpatterns = [
     path('', include(router.urls)),