orin-status: clean poweroff when the UPS pack stays low while discharging

--poweroff-below V --poweroff-after N (deployed: 11.0 V, 30 readings at 1/s).
Charging or a missing reading restarts the count. Publishes 'stopping' first;
poweroff through svc-gw's polkit grant, no sudo.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz

README.md

@@ -21,7 +21,7 @@ needed.
 | `obd-poller` | `yukart-obd-poller.service` | OBD-II mode 01 on the K-line through the Bluetooth ELM327 (address in `/etc/default/yukart-elm`), the single writer to the car; never on CAN. The `obd_*` signals, calibration references (`yukart/vehicle/*`): rpm, speed, throttle, load, MAF, timing, O2 every round; temperatures and trims every 5 s. Lets go of the adapter after a minute of ECU silence |
 | `gnss` | `yukart-gnss.service` | gpsd's fix as single values on `yukart/gnss/*`: fix, speed, heading, position, altitude, satellites |
 | `imu` | `yukart-imu.service` | The WT61 (plus) on any USB-UART adapter, found by itself (adapter and speed), turned into the car's frame (`--forward`, `--right`): roll, pitch, gravity-free longitudinal and lateral g, yaw rate on `yukart/imu/*`, at most every 40 ms. Never writes to the module |
-| `orin-status` | `yukart-orin-status.service` | The Orin's health on the bus, once a second: temperatures, CPU/GPU load, memory, power, fan, WiFi (with SSID)/LTE/tablet links, the CAN interface, the ELM's Bluetooth link, UPS battery (`yukart/host/*`) |
+| `orin-status` | `yukart-orin-status.service` | The Orin's health on the bus, once a second: temperatures, CPU/GPU load, memory, power, fan, WiFi (with SSID)/LTE/tablet links, the CAN interface, the ELM's Bluetooth link, UPS battery (`yukart/host/*`). Powers the Orin off cleanly when the UPS pack stays below 11.0 V while discharging for 30 s |
 
 ```bash
 scripts/deploy-recorder.sh                 # build, glibc check, install on the car Orin