Add JWT auth with per-user data isolation and account settings.

Users can register, log in, and manage profile/password in a personal account page; server data is scoped by owner across contacts, maps, tags, and import.

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

backend/import_export/urls.py

@@ -3,5 +3,5 @@ from django.urls import path
 from . import views
 
 urlpatterns = [
-    path('import/', views.import_contacts, name='import-contacts'),
+    path('import/', views.ImportContactsView.as_view(), name='import-contacts'),
 ]