How can I gracefully close a Node.js Redis client connection and ensure it's disconnected?

To gracefully close a Node.js Redis client connection, use the `quit()` or `disconnect()` method provided by the client library. `quit()` attempts to finish ongoing operations before disconnecting, while `disconnect()` forces an immediate disconnection. After calling either, you can check the `isOpen` property (or listen for the `'end'` event) to confirm the disconnection.