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-waybar-gpustat

@@ -4,7 +4,8 @@
 
 while :
 do
-  GPU_STAT=$(cat /sys/class/hwmon/hwmon5/device/gpu_busy_percent 2>/dev/null || echo "0")
+  GPU_STAT=$(cat /sys/class/hwmon/hwmon*/device/gpu_busy_percent 2>/dev/null | head -1 || echo "0")
+  GPU_STAT="${GPU_STAT:-0}"
   ICON="<span color='#69ff94' size='8pt' rise='1.5pt'>▁</span>"
 
   if [ "$GPU_STAT" -lt 10 ]; then