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>

failover/sync-usb-backup.sh.bak

@@ -0,0 +1,68 @@
+#!/usr/bin/env bash
+# Refresh the USB disk (sda) as a live boot-fallback clone of the
+# running root filesystem. Run manually after a push:
+#   sudo ./failover/sync-usb-backup.sh
+#
+# EEPROM BOOT_ORDER falls back to the SD card, then this USB disk, if the
+# primary boot disk (NVMe) doesn't come up. /etc/fstab, /etc/machine-id,
+# and /var/log are excluded from the sync so the clone keeps its own
+# partition identity (PARTUUIDs differ per disk) and boot/journal history
+# instead of inheriting the source disk's — see failover/README or repo
+# memory "sd-fallback-fstab-clobber" for what breaks if those leak across.
+set -euo pipefail
+
+[ "$(id -u)" -eq 0 ] || { echo "Run as root (sudo)." >&2; exit 1; }
+
+USB_ROOT_PART=/dev/sda2
+MOUNT_POINT=/mnt/usb-backup-root
+MOUNT_POINT=10.42.0.44:/media/andreas/writable-nvme
+
+
+[[ "$MOUNT_POINT" == *":"* ]]
+LOCAL_MOUNT=$?
+
+root_src=$(findmnt -no SOURCE /)
+if [ "$root_src" = "$USB_ROOT_PART" ]; then
+    echo "Currently booted from $USB_ROOT_PART — refusing to sync USB onto itself." >&2
+    exit 1
+fi
+
+if [ $LOCAL_MOUNT -eq 1 ]; then
+	mkdir -p "$MOUNT_POINT"
+	mounted_here=0
+	if ! mountpoint -q "$MOUNT_POINT"; then
+	    mount "$USB_ROOT_PART" "$MOUNT_POINT"
+	    mounted_here=1
+	else
+	    mount -o remount,rw "$MOUNT_POINT"
+	fi
+
+	cleanup() {
+	    if [ "$mounted_here" -eq 1 ]; then
+	        umount "$MOUNT_POINT"
+	    fi
+	}
+	trap cleanup EXIT
+fi
+
+# rsync exit 24 ("partial transfer due to vanished source files") is expected on a
+# live root — files like container shm sockets or in-progress logs routinely disappear
+# mid-sync. Tolerate that one code; anything else is a real failure and still aborts.
+rc=0
+rsync -aHAX --numeric-ids --delete \
+    --info=progress2 \
+    --exclude=/proc/* --exclude=/sys/* --exclude=/dev/* --exclude=/run/* \
+    --exclude=/tmp/* --exclude=/mnt/* --exclude=/media/* --exclude=/lost+found \
+    --exclude=/boot/firmware/* --exclude=/swapfile \
+    --exclude=/etc/fstab --exclude=/etc/machine-id --exclude=/var/log/* \
+    --stats / "$MOUNT_POINT/" || rc=$?
+
+if [ "$rc" -ne 0 ] && [ "$rc" -ne 24 ]; then
+    echo "rsync failed (exit $rc)." >&2
+    exit "$rc"
+fi
+if [ "$rc" -eq 24 ]; then
+    echo "Note: some files vanished mid-sync (rsync exit 24) — normal on a live root." >&2
+fi
+
+echo "USB backup ($USB_ROOT_PART) synced from $root_src."