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/21-van-br0.network.bak

@@ -0,0 +1,16 @@
+# The LAN gateway IP now lives on the bridge, not on the AP wlan (which is just a
+# bridge member). ConfigureWithoutCarrier keeps 10.42.0.1 up even before any wired
+# device is plugged, exactly as it was on the wlan-only setup.
+[Match]
+Name=br0
+
+[Link]
+RequiredForOnline=no
+
+[Network]
+Address=10.42.0.1/24
+ConfigureWithoutCarrier=yes
+# Resolve .local (mDNS) for devices on the van's own LAN (ESPHome nodes,
+# etc.) — scoped to br0 only, not the WAN links, since mDNS is link-local
+# and that's the only interface those devices are actually on.
+MulticastDNS=yes