feat: add dark mode, navigation, and Web Vitals tracking to marketplace

Backend:
- Simplify DatabaseConfig: remove effective_url property and project root finder
- Update to Pydantic v2 model_config (replace nested Config class)
- Add web_vitals router to main.py and __init__.py
- Fix ExplorerService datetime handling (ensure timezone-naive comparisons)
- Fix status_label extraction to handle both enum and string job states

Frontend (Marketplace):
- Add dark mode toggle with system preference detection

website/docs/clients.html

@@ -388,7 +388,7 @@ curl -X GET https://aitbc.bubuit.net/api/v1/jobs/JOB_ID \
                 <ul>
                     <li><strong>Documentation</strong>: <a href="full-documentation.html">Full API reference</a></li>
                     <li><strong>Community</strong>: <a href="https://discord.gg/aitbc">Join our Discord</a></li>
-                    <li><strong>Email</strong>: <a href="mailto:aitbc@bubuit.net">aitbc@bubuit.net</a></li>
+                    <li><strong>Email</strong>: <a href="mailto:andreas.fleckl@bubuit.net">andreas.fleckl@bubuit.net</a></li>
                     <li><strong>Status</strong>: <a href="https://status.aitbc.bubuit.net">System status</a></li>
                 </ul>
 
@@ -415,7 +415,7 @@ curl -X GET https://aitbc.bubuit.net/api/v1/jobs/JOB_ID \
                 <h2>Frequently Asked Questions</h2>
                 
                 <div class="alert alert-info">
-                    <strong>Question not answered?</strong> Contact us at <a href="mailto:aitbc@bubuit.net">aitbc@bubuit.net</a>
+                    <strong>Question not answered?</strong> Contact us at <a href="mailto:andreas.fleckl@bubuit.net">andreas.fleckl@bubuit.net</a>
                 </div>
 
                 <h3>General</h3>