feat: add profile edit

Profile page at /profile with first name, last name, display name, telephone and mobile read from AD and shown with the username and e-mail. Only changed fields are written through the directory adapter in one transaction with the audit entry (field names only); numbers are accepted in any common notation and stored as +country code and digits; names are required. Plain-language errors per field, German text and tests; review findings logged in the plan.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FocPJ75XPma7TcuYEMy8zm

portal/profile/urls.py

@@ -3,6 +3,7 @@ from django.urls import path
 from . import views
 
 urlpatterns = [
+    path("profile", views.profile, name="profile"),
     path("password", views.password, name="password"),
     path("password/done", views.password_done, name="password-done"),
 ]