[FEATURE REQUEST] Don't require git to reply to the last AI message

Low priority — I know there's a lot on the issue tracker already.

One thing I really like in the Codex app is the ability to reply to parts of a message. Your current implementation works well, but it only functions inside a git repository. However, this situation doesn't always hold — I sometimes want to reply to a portion of the AI's response when I'm not in a repo.

I don't need this for any other feature — only for plannotator-last