[android] Back Button does nothing

(not sure if this is the best place to report this. Happy to move it to Github issues, but haven’t seen a repo for the android client. Anyway…)

Android hardware Back button does nothing in Volumio app.

Expected, if a “back” navigation button is visible in Browse Tab, app should go back/up one level.
If in settings or at top level of Browse Tab, Back button should return to Playback tab.
If in Playback Tab, Back Button should return user to Android Homescreen.

Actual: Button does nothing.