Recovery now has a stated policy for sessions whose tmux pane is gone but
whose sidecar survived: dormant (default), auto, or never. auto goes down
the same SessionManager::resume the client's POST takes, so there is one
resume path. never prunes the sidecars the way #163 does for a missing cwd.
The default is dormant because resuming agents unattended seconds after a
reboot is a foot-gun; auto is opted into per host. Recovery logs which
policy ran and how many sessions it acted on.
Refs #167
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
