Update configuration and enhance newsletter generation features

- Change WIKI_API_URL in .env.example and config to point to the new API endpoint.
- Set COOKIE_SECURE to false for local development in .env.example and config.
- Improve the newsletter generation logic to handle new and edited articles separately.
- Add display options for showing date, user, and category in the newsletter output.
- Enhance error handling for Wiki API requests and update templates for better user feedback.
- Update CSS for new UI elements and improve overall layout in dashboard and login pages.

.env.example

@@ -7,8 +7,9 @@ HOST_PORT=8080
 DATABASE_URL=sqlite:///./data/newsletter.db
 # Beispiel PostgreSQL:
 # DATABASE_URL=postgresql+psycopg://newsletter:newsletter@postgres:5432/newsletter
-WIKI_API_URL=https://www.thomas-krenn.com/de/wiki/api.php
+WIKI_API_URL=https://www.thomas-krenn.com/de/wikiDE/api.php
 ALLOWED_HOSTS=*
-COOKIE_SECURE=true
+COOKIE_SECURE=false
+# Auf true setzen, wenn hinter HTTPS/TLS-Terminierung (Reverse Proxy)
 ADMIN_BOOTSTRAP_EMAIL=admin@internal.local
 ADMIN_BOOTSTRAP_PASSWORD=ChangeMe123!