Add public tunnel management and fix connection stability issues
- Add Tunnels block to settings with Local Server, Cloudflare Quick Tunnel, and ngrok support
- Implement one-click tunnel install, enable, stop, and delete actions
- Persist tunnel PID and public URL state across panel restarts
- Improve tunnel process detection and cleanup on Windows, Linux, and Docker
- Add tunnel translations and README documentation
- Fix settings save 422 when server list is empty and Remnawave auto-create is disabled
- Fix AWG Legacy config path resolution by detecting actual wg0.conf/awg0.conf inside container
- Fix Xray client add/toggle/remove flow to use runtime API without restarting the container
- Fix WireGuard Show config calls by routing get_client_config through the unified manager adapter