Fix Traefik configuration issues and improve security

- Upgrade to traefik:latest to fix Docker API compatibility with v29
- Fix websecure entrypoint indentation in traefik.yml
- Remove obsolete DOCKER_API_VERSION environment variable
- Remove incompatible network_mode: host setting
- Set network to external for multi-compose compatibility
- Add environment variable support for certificate email
- Add acme.json to .gitignore for security
- Create acme.json with correct 600 permissions

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.env.example

@@ -1,3 +1,4 @@
 DASHBOARD_HOST=
 DASHBOARD_USER=
 DASHNOARD_PASSWORD=
+CERT_EMAIL=