End game if only AI remains

It would be nice to have an option have the human players (or the server) end a game if only AI players are left. Sometimes I'd like to see which one wins, but often I would prefer to free up the resources.

I think this might be a duplicate of another open issue, but I couldn't find which one based on some searching.

The issue names no files, tests, or entry points. Start by searching for game-end handling and AI-player detection, then determine where a human or server option belongs. Done means the behavior is configurable, games with only AI players can end when requested, and the existing option to let them continue remains available.

Written by the indexing model from the issue text.