A host reboot kills the tmux server, so `SessionManager::recover` iterated an
empty list and every session vanished from the API while its sidecar sat
untouched on disk. A second recovery pass now reads the sidecars tmux had
nothing to adopt and registers each as `SessionStatus::Dormant` — a record of
what was running, with no pane and no PTY bridge behind it.
`SessionStatus` deserializes leniently now, like `ActivityState`: an unknown
spelling reads as `Dead` rather than failing the whole `Session`.
Refs #162
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>