dispose method
Closes all connections and cleans up resources
Implementation
Future<void> dispose() async {
// (_connManager as ConnectionManager).dispose(); // If it has a dispose method
// Or iterate through active connections and close them if not managed by ConnManager directly.
// For now, assuming ConnManager handles its own cleanup or this is done at a higher level.
print('TCPTransport dispose called. ConnManager should handle connection cleanup.');
}