Treehouse, isolate multple dev environments on different Git worktrees

Treehouse assigns stable numbers to Git worktrees enabling per-worktree configuration like port assignments and database names. Each worktree's number is stored in.treehouse within the worktree's git-dir metadata. Commands like treehouse offset and treehouse current retrieve or set worktree numbers for port mapping and environment isolation. Developers use treehouse init to set worktree numbers and treehouse run to execute commands with WORKTREE_NUMBER set. Worktree numbers are not checked in and are removed when worktrees are deleted.