Adding "back" button to Weather app (matching Agenda, Health, etc)?

or setUI({back}) on Bangle.js 1 ends up being a bit useless

I don't think it's quite that bad: touching the left-hand side of the screen works fine, and most apps do use the buttons anyway. But for those that don't, it would be nice if this worked.

BTN2 seemed natural, but now you mention BTN3, that would make sense
short-press: go back
long-press: go all the way back