feat: Add basic user handling

src/templates/django_registration/registration_form.html

@@ -0,0 +1,15 @@
+{% extends "fellchensammlung/base_generic.html" %}
+{% load i18n %}
+
+{% block content %}
+{% if not user.is_authenticated %}
+  <form method="post" action=".">
+    {% csrf_token %}
+    {{ form.as_p }}
+
+    <input type="submit" value="{% translate 'Submit' %}" />
+  </form>
+{% else %}
+  <p>{% translate "You're already logged in." %}</p>
+{% endif %}
+{% endblock %}