v3.2.0

• Calibration now needs the whole bed to be empty, not only the side being
  calibrated. It picked its quiet stretch by looking at its own side alone, so a
  side could calibrate while someone lay on the other one and measure their
  movement coming through the mattress instead of an empty bed. A stretch is now
  skipped if either side recorded a heart rate during it. When the bed was busy
  the whole time, calibration waits for another day rather than settling for the
  least busy stretch.

• The calibration quality score now drops when the window it learned from was
  thin. Every second was being counted twice, so a window missing half its
  readings scored the same as a full one. Calibration also measures each side's
  signal level on an empty bed and keeps that with every run. It is recorded
  only, and does not change how presence is detected yet.

• An update could leave the server running without database tables it needs.
  The database step ran while the biometrics service was still writing to the
  same file and could not get the lock it needed. That was logged as a warning,
  and the check after the update passed anyway, because it confirms the server
  answers, reports the right version and reads a sensor, and none of that
  touches the new tables. On one pod this left calibration failing every night
  until it was fixed by hand. Updates now pause the biometrics service while the
  database is updated, retry, confirm nothing is left pending, and roll back if
  it still did not apply. This protects updates made from this version on. The
  update that installs this version runs the updater already on the pod, so it
  does not get the fix itself.

• Each time presence starts, the minute that follows is now recorded along with
  the few seconds before it. A person settles well above the level that starts a
  session, while an empty side that briefly crossed it drops back within
  seconds, so the log now shows which sessions were real without keeping raw
  sensor recordings around.

• scripts/setup_watchdog.sh turns on the pod's hardware watchdog, so a frozen
  system restarts itself within about 30 seconds. On one pod a fault in the
  stock Wi-Fi driver froze the system partway through its nightly restart, and
  it stayed down, with no server and no cooling, until it was unplugged. Updates
  do not run this script. It is run once, as root, on the pod.