feat: insurance section — overview, documents, analysis, KVG premium comparison

- Insurance overview page (/insurance): current policies table with type,
  provider, premium, franchise, coverage, and document links
- Documents page: upload and manage insurance documents
- Analysis page: coverage gap analysis per insurance type
- Priminfo integration (/insurance/priminfo): KVG premium comparison by
  insurer, model (TAR/HMO/etc.), franchise level, and accident coverage
  via embedded Priminfo iframe (no public API available)
- Backend: Insurance, PraemienEntry, PraemienPolice models with migrations
- Sidebar: insurance nav group with flyout and dropdown
- i18n: all keys in DE/EN/FR/IT

backend/core/urls.py

@@ -7,7 +7,7 @@ from rest_framework.routers import DefaultRouter
 from rest_framework_simplejwt.views import TokenRefreshView
 from finance.views import (
     AccountViewSet, TransactionViewSet, BudgetViewSet,
-    ExpenseViewSet, DeadlineViewSet, ProfileView, RegisterView, LogoutView, ChangePasswordView,
+    ExpenseViewSet, DeadlineViewSet, InsuranceViewSet, PraemienView, PraemienVergleichView, ProfileView, RegisterView, LogoutView, ChangePasswordView,
     ICalUrlView, ICalFeedView, NotificationsView, SearchView,
     LoginView, TwoFactorLoginView, TwoFactorSetupView, TwoFactorEnableView, TwoFactorDisableView,
     TwoFactorRecoverRequestView, TwoFactorRecoverConfirmView,
@@ -22,6 +22,7 @@ router.register(r'transactions', TransactionViewSet, basename='transaction')
 router.register(r'budgets', BudgetViewSet, basename='budget')
 router.register(r'expenses', ExpenseViewSet, basename='expense')
 router.register(r'deadlines', DeadlineViewSet, basename='deadline')
+router.register(r'insurances', InsuranceViewSet, basename='insurance')
 
 _admin_url = os.environ.get('ADMIN_URL', 'manage/').strip('/')+ '/'
 
@@ -50,6 +51,8 @@ urlpatterns = [
     path('api/notifications/prefs/', NotificationPrefsView.as_view()),
     path('api/search/', SearchView.as_view()),
     path('api/notifications/', NotificationsView.as_view()),
+    path('api/praemien/', PraemienView.as_view()),
+    path('api/praemien/vergleich/', PraemienVergleichView.as_view()),
     path('api/calendar/ical-url/', ICalUrlView.as_view()),
     path('api/calendar/ical/<int:user_id>/<str:token>/', ICalFeedView.as_view()),
 ] + static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)