stop static method
Stops the HTTP server and removes the lifecycle observer.
Implementation
static Future<void> stop() async {
if (!_isRunning || _server == null) return;
WidgetsBinding.instance.removeObserver(_observer);
await _server!.close(force: true);
_server = null;
_isRunning = false;
Log.i('[Server] 🛑 Stopped');
}