Greater control over bots

Ideas:
- Skip the rest of move calculations, and just use what is already calculated (if stuck on e.g. 7th out of 10 moves)
- Manual moves, possibly by showing the possible moves ranked instead of just moving automatically
- Greater details during calculation, e.g. show what move is being worked on, either in text or visually on the board

Benefits:
- Makes it easier to 'debug' the bot
- Interesting implementation difficulties
- Could evolve into an analysis mode similar to the ones available on Lichess and Chess.com

Start by reading the minimax AI opponent and mapping where move calculation currently happens. Narrow the ideas to one agreed control, such as interrupting calculations or selecting ranked manual moves; done means that behavior is implemented and demonstrable without disrupting normal play.

Written by the indexing model from the issue text.