fix: configure CI database connection properly

- Add dotenv loading to Django settings
- Update CI workflow to use correct environment variables
- Set POSTGRES_* variables instead of DATABASE_URL
- Add environment variables to all Django management commands
- Fixes CI test failures due to database connection issues

app/templates/stiftung/foerderung_detail.html

@@ -26,9 +26,13 @@
                         <div class="col-md-6">
                             <h6 class="text-primary">Person</h6>
                             <p class="mb-3">
+                                {% if foerderung.destinataer %}
                                 <a href="{% url 'stiftung:destinataer_detail' foerderung.destinataer.pk %}">
-                                    {{ foerderung.person.get_full_name }}
+                                    {{ foerderung.destinataer.get_full_name }}
                                 </a>
+                                {% else %}
+                                <em class="text-muted">Keine Person zugeordnet</em>
+                                {% endif %}
                             </p>
                             
                             <h6 class="text-primary">Jahr</h6>