feat(proxy): add Traefik version tracking with notifications and dismissible UI warnings

- Add automated Traefik version checking job running weekly on Sundays
- Implement version detection from running containers and comparison with versions.json
- Add notifications across all channels (Email, Discord, Slack, Telegram, Pushover, Webhook) for outdated versions
- Create dismissible callout component with localStorage persistence
- Display cross-branch upgrade warnings (e.g., v3.5 -> v3.6) with changelog links
- Show patch update notifications within same branch
- Add warning icon that appears when callouts are dismissed
- Prevent duplicate notifications during proxy restart by adding restarting parameter
- Fix notification spam with transition-based logic for status changes
- Enable system email settings by default in development mode
- Track last saved/applied proxy settings to detect configuration drift

app/Models/Server.php

@@ -167,6 +167,7 @@ class Server extends BaseModel
         'hetzner_server_id',
         'hetzner_server_status',
         'is_validating',
+        'detected_traefik_version',
     ];
 
     protected $guarded = [];