fix(update): the legacy start_watchdog matches the monitor exactly too; a restart is reported only when the monitor runs (Issue #72, review round 4)

With MAM_DELEGATION_PY=0 the legacy helper still found the monitor with an
unanchored pgrep -f, so a process that only named the monitor path was
reported as the restarted monitor and none was started. lib.sh _monitor_pids
is the shell twin of daemon.find_running; update.sh and post_update.sh check
the PID start_watchdog printed with mam_monitor_started before saying
"monitor: restarted".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.agents/skills/multi-agent-mux-update/scripts/update.sh

@@ -104,6 +104,8 @@ _restart_monitor() {
   fi
   local pid
   pid=$(start_watchdog update "$WS") || { echo "ERROR: could not restart the monitor daemon" >&2; return 1; }
+  # shellcheck disable=SC2086
+  mam_monitor_started "$WS" $pid || { echo "ERROR: could not restart the monitor daemon (PID ${pid:-none} is not its monitor)" >&2; return 1; }
   echo "monitor: restarted (PID $pid)"
 }