Upsert directory on session continue, emit event for change

[sanchitrk]

From codex:

Choose working directory to resume this session

  Session = latest cwd recorded in the resumed session
  Current = your current working directory

codex seems to prompt for cwd change, so it maintains cwd state, as we do. For now, I think its good to know that cwd has changed for session, and continue rather than interrupt. Basically fuckup in fuckup out.

It's up to the user to just mess up the directory with diff source context, nothing stops user to copy, rm bunch of files even in same directory.