Fix watchdog timeout and MQTT connectivity issues

Problem: R5C spontaneously rebooted due to hardware watchdog timeout
Cause 1: van-gps-owntracks in infinite restart loop (MQTT connect failed)
Cause 2: mosquitto only listening on localhost, so clients couldn't connect
Solution:
- Add restart limits to van-gps-owntracks and van-li3-battery services
  (max 3 restarts per 5 minutes prevents infinite restart loops)
- Configure mosquitto to listen on all interfaces (0.0.0.0:1883)
- Deploy mosquitto listener config via deploy.sh
- Restart mosquitto during deploy to apply config changes

This prevents the system from hitting the 11-second hardware watchdog timeout
when services crash and systemd auto-restarts them indefinitely.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

deploy.sh

@@ -227,6 +227,11 @@ install_rendered router-status/config.json              /etc/van-router-mqtt/con
 install -D -m0644 router-status/van-router-mqtt.service /etc/systemd/system/van-router-mqtt.service
 python3 -c 'import paho.mqtt' 2>/dev/null \
     || warn "python3-paho-mqtt missing (apt install python3-paho-mqtt) — van-router-mqtt won't start"
+# MQTT broker must listen on all interfaces (not just localhost) for clients on br0
+install -D -m0644 router-status/mosquitto-listener.conf /etc/mosquitto/conf.d/van-listener.conf
+# Restart limit drop-ins: prevent infinite restart loops that trigger hardware watchdog
+install -D -m0644 router-status/van-gps-owntracks-restart-limit.conf /etc/systemd/system/van-gps-owntracks.service.d/restart-limit.conf
+install -D -m0644 li3/van-li3-battery-restart-limit.conf /etc/systemd/system/van-li3-battery.service.d/restart-limit.conf
 
 echo "== gps (cellular modem GNSS -> gpsd) =="
 if dpkg -s gpsd >/dev/null 2>&1; then
@@ -308,6 +313,7 @@ systemctl daemon-reexec
 # an already-up WAN keeps its currently-applied DNS until it reconnects (or
 # reboot), deliberately not forced here (reconnecting a WAN flaps it).
 systemctl restart systemd-resolved
+systemctl restart mosquitto
 # networkd here owns only the AP radios + bridge + wired LAN port (no real uplink);
 # its wait-online would just stall network-online.target. NM-wait-online covers WANs.
 systemctl mask systemd-networkd-wait-online.service >/dev/null 2>&1 || true