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>

ap/20-van-br0.netdev.bak

@@ -0,0 +1,11 @@
+# LAN bridge: joins the AP Wi-Fi radios (added by hostapd, once in AP mode) and the
+# wired LAN ports (enx00e04c331140 + onboard eth0, added by networkd) into one
+# 10.42.0.0/24 segment. STP off: all members are leaf ports, no loops (don't cable
+# the two wired ports to the same switch), and it avoids the forwarding delay that
+# would otherwise stall the first DHCP handshake on a freshly-plugged client.
+[NetDev]
+Name=br0
+Kind=bridge
+
+[Bridge]
+STP=no