Add Pi hardware watchdog setup

Co-authored-by: Copilot <[email protected]>

deploy/install_watchdog.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+# Enable systemd's hardware watchdog on the Pi.
+# Run this ON THE PI as the `yaris` user:
+#   cd /home/yaris/app/yaris-obd && bash deploy/install_watchdog.sh
+set -euo pipefail
+
+REPO_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+CONFIG_FILE="$REPO_DIR/deploy/yaris-watchdog.conf"
+CONFIG_DIR="/etc/systemd/system.conf.d"
+CONFIG_DEST="$CONFIG_DIR/yaris-watchdog.conf"
+
+if [ ! -e /dev/watchdog0 ]; then
+    echo "No /dev/watchdog0 device found; refusing to enable a watchdog."
+    exit 1
+fi
+
+sudo install -D -m 0644 "$CONFIG_FILE" "$CONFIG_DEST"
+
+# Manager configuration is not covered by daemon-reload. Re-exec systemd so the
+# watchdog starts now without requiring an otherwise unnecessary reboot.
+sudo systemctl daemon-reexec
+
+runtime_watchdog="$(systemctl show --property=RuntimeWatchdogUSec --value)"
+if [ "$runtime_watchdog" = "0" ]; then
+    echo "Runtime watchdog did not activate; check $CONFIG_DEST."
+    exit 1
+fi
+
+echo "Hardware watchdog enabled with RuntimeWatchdogUSec=$runtime_watchdog."
+echo "Reboot once when convenient, then rerun this script to verify persistence."

deploy/yaris-watchdog.conf

@@ -0,0 +1,3 @@
+[Manager]
+RuntimeWatchdogSec=10s
+RebootWatchdogSec=10min