If a first archive attempt removed git's admin dir but failed to clean the
working tree (e.g. due to file churn during setup), retrying the archive
failed the ownership gate with "Worktree is not a Paseo-owned worktree"
because isPaseoOwnedWorktreeCwd required the worktree to still appear in
git worktree list.
- isPaseoOwnedWorktreeCwd now decides ownership by path shape
($PASEO_HOME/worktrees/<hash>/<slug>[/...]) and treats git as
best-effort for resolving repoRoot.
- deletePaseoWorktree tolerates a missing admin dir: it skips teardown
when the tree is absent, swallows a failing git worktree remove so
the rmSync fallback always runs, and follows up with git worktree
prune to clear stale admin refs.
- Relabel the post-creation setup failure log as
"Background worktree setup failed" since the worktree itself already
exists at that point.