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-clipboard

@@ -2,7 +2,7 @@
 # ABOUTME: Rofi-based clipboard history manager using cliphist and wl-copy.
 # ABOUTME: Lists clipboard entries and copies the selected one.
 
-CLIPHIST_DB="/run/user/1000/cliphist/db"
+CLIPHIST_DB="${XDG_RUNTIME_DIR:-/run/user/$(id -u)}/cliphist/db"
 
 function start_rofi() {
     local content="$1"