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-capsnote

@@ -4,9 +4,9 @@
 
 sleep 0.2
 
-value=($(cat /sys/class/leds/input*::capslock/brightness | cut -f1 -d,))
+value=($(cat /sys/class/leds/input*::capslock/brightness 2>/dev/null | cut -f1 -d,))
 
-if [ ${value[2]} == 1 ]; then
+if [ "${value[0]:-0}" == 1 ]; then
   icon_name="capslock-enabled-symbolic"
   output="caps lock on"
 else
@@ -16,4 +16,4 @@ fi
 
 notify-send -e "$output" -i "$icon_name" \
   -h string:x-canonical-private-synchronous:state \
-  -h boolean:value:"${value[2]}" -r 555
+  -h boolean:value:"${value[0]:-0}" -r 555