Fix audit findings, replace wlogout with moonset

Bug fixes from quality and security audits:
- moonarch-capsnote: use value[0] instead of value[2]
- moonarch-btnote: guard empty PER_INT before integer comparison
- moonarch-clipboard + niri config: use XDG_RUNTIME_DIR instead of UID 1000
- moonarch-waybar-hidpp: use charging icon when charging
- moonarch-waybar-gpustat: find gpu_busy_percent dynamically across hwmon*
- post-install/transform: use systemctl --user cat for service detection
- post-install/transform: install paru from [extra] instead of AUR clone

Replace wlogout with moonset in niri keybind and waybar on-click.
Remove moonarch-session (dead code, replaced by moonset) and wlogout
layout config.

defaults/bin/moonarch-btnote

@@ -11,7 +11,7 @@ for d in $(upower -e); do
   PER_INT=$(echo "${PERCENTAGE//%}")
   DEVICE_NAME=$(echo $DEVICE_DATA | grep -Po '(?<=(model: )).*(?= serial)')
 
-  if [ ! -z "$DEVICE_NAME" ] && [ "$PER_INT" -lt "$NOTIFY_AT_PERCENTAGE" ]; then
+  if [ -n "$DEVICE_NAME" ] && [ -n "$PER_INT" ] && [ "$PER_INT" -lt "$NOTIFY_AT_PERCENTAGE" ]; then
     notify-send -t 5000 -e "Low battery $DEVICE_NAME $PER_INT%" -i "$ICON" \
       -h string:x-canonical-private-synchronous:battery \
       -h int:value:"$PER_INT" -u critical