Please add Hint button for puzzles

[Sadsnake1]

Right now is only possible with view solution.

It would be nicer though if we could have a hint button to just highlight the piece that needs moving.

[alecmagnani]

I'm interested in taking a crack at this if maintainers agree it's a good add. fwiw I've wanted this too.

My first thought as someone new to this project is it makes sense as an addition to the frontend/ui, highlighting the starting square of the next move in the solution (i.e. emphasizing the piece to move but not showing an arrow or anything).

Assuming it doesn't warrant an addition to the api so it returns e.g. a list of hints alongside the solution moves.