Add optional Home Assistant integration for battery percentage tracking

sbin/install-service.sh

@@ -36,6 +36,13 @@ HOST="${HOST:-127.0.0.1}"
 read -rp "Listen port [default: 5000]: " PORT
 PORT="${PORT:-5000}"
 
+echo
+echo "Home Assistant integration (optional — press Enter to skip):"
+read -rp "  HOMEASSISTANT_URL (e.g. http://homeassistant.local:8123): " HA_URL
+read -rp "  HOMEASSISTANT_API_KEY (long-lived access token): " HA_KEY
+read -rp "  HOMEASSISTANT_POLL_INTERVAL seconds [default: 300]: " HA_INTERVAL
+HA_INTERVAL="${HA_INTERVAL:-300}"
+
 echo
 echo "Generating service file → $SERVICE_FILE"
 
@@ -51,6 +58,9 @@ Type=simple
 WorkingDirectory=$APP_DIR
 ExecStart=$VENV_WAITRESS --host=$HOST --port=$PORT app:app
 Environment=PYTHONPATH=$APP_DIR
+$([ -n "$HA_URL" ] && echo "Environment=HOMEASSISTANT_URL=$HA_URL")
+$([ -n "$HA_KEY" ] && echo "Environment=HOMEASSISTANT_API_KEY=$HA_KEY")
+$([ -n "$HA_URL" ] && echo "Environment=HOMEASSISTANT_POLL_INTERVAL=$HA_INTERVAL")
 Restart=on-failure
 RestartSec=5