feat：新增gps监控服务（断开重连）

scripts/boot/README.md

@@ -77,6 +77,10 @@ BLITZ_HEALTH_STALE_SEC="15"
 BLITZ_OMNID_THREAD_HEARTBEAT_TIMEOUT_SEC="15"
 BLITZ_NETWORK_FAIL_THRESHOLD="3"
 BLITZ_NETWORK_RECOVERY_COOLDOWN_SEC="30"
+BLITZ_GPS_MONITOR_ENABLED="1"
+BLITZ_GPS_DEVICE_GLOB="/dev/ttyCH341USB*"
+BLITZ_GPS_CHECK_INTERVAL_SEC="10"
+BLITZ_GPS_RESTART_UNITS="gpsd.socket gpsd.service"
 BLITZ_WATCHDOG_ALLOW_FAULT_INJECTION="0"
 ```
 
@@ -157,6 +161,8 @@ Key files:
 - `ros-receiver.status.json`
 - `watchdog.status.json`
 
+`watchdog.status.json` now also records `gps_ok` and `gps_device_present` so you can quickly tell whether the GPS USB serial node is currently visible and whether the last `gpsd` reconnect attempt succeeded.
+
 Pretty-print them:
 
 ```bash
@@ -201,6 +207,7 @@ sudo bash scripts/boot/blitz-fault-inject.sh network-down off
   - wait for unix socket
   - start `b_side`
 - If network checks fail repeatedly, watchdog stops `b_side`, runs `5g-dial.sh`, waits for route recovery, and then restores services.
+- If GPS monitoring is enabled, watchdog checks `BLITZ_GPS_DEVICE_GLOB` every `BLITZ_GPS_CHECK_INTERVAL_SEC` seconds. When the GPS serial device disappears and later reappears, watchdog restarts the units in `BLITZ_GPS_RESTART_UNITS` so `gpsd` can bind to the new device node again.
 - Camera disappearance is logged as degraded state. Reappearance triggers a `b_side` restart after the device is stable.
 
 ## Notes