VERK

Worktree cache location

Set VERK_WORKTREE_ROOT to force where per-ticket worktree caches are created.

If unset, path resolution falls back in order to:

1. $XDG_CACHE_HOME/verk/worktrees
2. $HOME/.cache/verk/worktrees
3. os.TempDir()/verk/worktrees

The cache root is then namespaced by repository hash: <workRoot>/<repoHash>, where <repoHash> = sha256(abs(repoRoot))[:12]. Ticket worktrees are created at: <workRoot>/<repoHash>/<runID>/<ticketID>/.