[Feature Request] Add songs to and sync with local playlist

[atkirtland]

Description

I'd like to be able to automatically sync my playlists with files (e.g. in m3u format) kept locally that are readable with other software.

Solution

Add the ability to add songs to a local playlist generated through m3u, and automatically sync the changed playlist with the local m3u file.

Alternatives

N/A

Additional Context

This feature is present in a couple paid music players (Poweramp and Gonemad), but I haven't found it in any open source ones yet (let me know if anyone knows of any!). It would be very useful for syncing playlists with tools like Syncthing.

Checklist

• I have read the Contribution Guidelines.