Rabbitty Beta 0.1.0-beta.46

IMPORTANT FIX — your shell config works again. Release builds pointed zsh at a startup directory that was never created, so terminals loaded none of your config: no prompt, no aliases, no PATH. If Rabbitty's terminal felt broken, this was why. The startup dir is now only used after a write we verified succeeded.

Also: Grok is now a supported agent (status, transcripts, AI Trail). Browsers are per-lane — each project/worktree remembers its own page; lanes now start on the empty state rather than inheriting an unrelated project's URL, so expect a one-time reset.