#164 skipped the tmux probe whenever the stored boot id differed from the
current one, assuming a changed boot id proves the tmux server is gone. It
does not: a restored state directory, a VM or container snapshot rollback,
or a truncated boot_id file all change it while tmux keeps running with
live sessions. Every one of those sessions was then registered Dormant and
stranded — resume respawns `maestro-<id>`, which collides with the name
tmux still holds, so it failed 502 forever.
Recovery now always runs `tmux list-sessions`, the single source of truth
for liveness the rest of the daemon assumes. The boot id keeps its other
job: telling a reboot from a restart in recovery's log.
The #164 test asserted the old behaviour with tmux still alive, so it is
replaced by one asserting the session is adopted Running, plus one covering
a real reboot — boot id changed and the tmux server dead — still going
dormant.
Refs #174