Improve GitHub bot

[ErikBjare]

The bot should be a lot more capable to make code changes with Claude Sonnet 3.5, and now 3.7.

I should polish it and throw a few issues at it and see how it does.

Inspired by https://x.com/granawkins/status/1900917075708936594

Should also update the docs to make them less confusing: https://gptme.org/docs/bot.html

Maybe do https://github.com/gptme/gptme/issues/305