Fix dunst config loading, modernize notification handling

- Point dunst to /etc/xdg/dunst/dunstrc via -conf flag (dunst with
  SYSCONFDIR=/etc does not search XDG_CONFIG_DIRS)
- Update dunstrc: fix legacy offset syntax, replace missing
  Tela-purple-dark icon theme with Colloid-Grey-Catppuccin-Dark
- Replace dunstify with notify-send in moonarch-cpugov for
  daemon-agnostic notifications, fix broken icon path
- Replace dbus-monitor based moonarch-dnd script with inline
  waybar polling (interval 2s), fixing process accumulation bug
- Add #custom-dnd to waybar CSS padding rule

defaults/bin/moonarch-cpugov

@@ -64,7 +64,7 @@ then
     # Execute the choice
     ${COMMANDS[$choice]}
 
-    dunstify --replace 553 -i "/usr/share/icons/zafiro-dark/devices/48/cpu.svg" "CPU Mode" "Set to $choice ${LABELS[$choice]}"
+    notify-send -h string:x-canonical-private-synchronous:cpugov -i cpu "CPU Mode" "Set to $choice ${LABELS[$choice]}"
 else
     echo "Unknown command: ${choice}" | rofi -dmenu -p "error"
 fi