--include-unmanaged lifts only the location gate, and nothing proved the keep
gate still held behind it.
- assert a dirty hand-made worktree survives --include-unmanaged alone
Any git error on a directory under the worktree root was classified orphan,
and orphan deletes the directory outright, so a transient failure reading the
source root became data loss on a plain `agentws prune --yes`.
- prove a backing repo gone by stat before calling a directory an orphan
- classify an unexplained git failure as keep, naming the error
- refuse to remove a worktree whose git state is unknown, even with --include-keep
- spell out that --include-keep discards uncommitted and in-progress work
- discover worktrees from `git worktree list` on each source checkout, not only
the worktree root, so hand-made ones, stale registrations and orphaned
directories are classified too
- normalise each candidate to its main checkout, so a linked worktree in the
source root cannot offer up the repo's real checkout
- keep locked, mid-rebase and detached-with-unique-commits worktrees, whose
removal would destroy state nothing else holds
- name the retained branch in every unproven verdict
- add --no-fetch, --json, --include-unmanaged and --include-keep
unkin-agent