GrampsWeb Phase 1: Sidebar-Link, Settings-Fix & Env-Template (STI-90)

- Fix GRAMPS_URL default port from 80 to 5000 to match dev compose
- Add "Ahnenforschung" sidebar link in navigation (links to /ahnenforschung/)
- Update env-template with all GRAMPSWEB_* variables for production setup

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/templates/base.html

@@ -689,6 +689,10 @@
                 <i class="fas fa-book-open"></i>
                 <span>Geschichte</span>
             </a>
+            <a class="sidebar-link" href="/ahnenforschung/" target="_blank">
+                <i class="fas fa-tree"></i>
+                <span>Ahnenforschung</span>
+            </a>
             {% if perms.stiftung.access_administration %}
             <a class="sidebar-link" href="{% url 'stiftung:administration' %}">
                 <i class="fas fa-cogs"></i>