Module engine 

Audio playback engine.

Runs entirely on a dedicated std::thread — no tokio inside this module. The TUI communicates via two std::sync::mpsc channels:

• PlayerCommand (TUI → engine): play a URL, pause, resume, stop, set volume.
• PlayerEvent (engine → TUI): progress ticks, track-ended, errors.

Enums

PlayerCommand

Commands sent from the TUI to the player thread.

PlayerEvent

Events sent from the player thread back to the TUI.

Functions

spawn_player

Spawn the player thread.