Changing directory no longer calls the environment stale before any request was sent

What

When you move a session to another folder with /cd, or an app does so with the set_cwd control request, Claude receives a note about the move. The folder a session runs in is called its working directory.

• The note's sentence "The environment block at the start of this conversation still names the previous directory" is now included only when a request has already been built, as reported by a new requestBuilt callback, or when no callback is given. One caller always reports that no request was built.
• The result of the move now includes freshSession, which says whether the session was still fresh.
• set_cwd passes requestBuilt in and receives freshSession back.

Why

Before, the sentence was always included, so Claude could be told its starting information was out of date even though it had never been sent. Now Claude only gets that warning when it applies.