fix: keep terminal open after moonarch-update completes

Add "press any key" prompt when running interactively (stdin is a TTY).
Remove dead wrapper in defaults/bin/ that was overwritten by PKGBUILD.

defaults/bin/moonarch-update

@@ -1,7 +0,0 @@
-#!/usr/bin/bash
-# ABOUTME: Interactive system update wrapper for use as Waybar on-click action.
-# ABOUTME: Runs paru and waits for keypress before closing the terminal.
-
-paru
-echo
-read -n 1 -s -r -p "Press any key to close..."