Multi-Device Co-op Mode for UTAGE or Another Charts.

**Is your feature request related to a problem? Please describe.**
When attempting to play custom UTAGE charts that require collaboration on two devices, or when trying to simulate a synchronized co-op gaming experience, I find it challenging to start the game simultaneously on both devices.

**Describe the solution you'd like**
I propose a feature that allows multiple devices to connect via Wi-Fi or Bluetooth. With this connection, once all devices are ready and the play button is pressed, the chart will start playing simultaneously on all devices. The specific steps are as follows:

1. Players create or join a room.
2. The host selects the chart, and other devices receive the chart file from the host’s device via the local network.
3. Wait for all players to press the ready button.
4. After all players are ready, the game emits a prompt sound and starts simultaneously on all devices after three seconds.