Add toggle button for hidding non-audio files

[AObuchow]

Ideally, there should be some file filtering preferences, but for now, being able to only view supported audio files and directories in a file manager will work.

[webbrain-one]

Hi! I’ve opened a PR to address this: #52

It adds a toggle button to filter the file manager so only supported audio files and directories are visible. This covers the immediate request while we plan broader filtering preferences for later. Let me know your thoughts! Thanks!