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/templates/profile/details_unknown.html

@@ -0,0 +1,10 @@
+{% extends "base.html" %}
+{% load i18n %}
+{% block title %}{% trans "Result unclear" %}{% endblock %}
+{% block content %}
+<h1>{% trans "Result unclear" %}</h1>
+<div class="notice" role="alert">
+  <p>{% trans "Your details may have been changed, but the portal could not finish. Please open your profile and check them. If they are wrong, contact the administrator." %}</p>
+</div>
+<p><a class="button" href="{% url 'profile' %}">{% trans "Back to the profile" %}</a></p>
+{% endblock %}