Add 'mas' to Homebrew configuration in aarch64-darwin

This commit updates the default Homebrew configuration to include 'mas' alongside 'libusb' for the aarch64-darwin system. It also introduces an empty 'masApps' array for potential future use.

modules/darwin/system/homebrew/default.nix

@@ -1,4 +1,9 @@
-{ lib, config, inputs, ... }:
+{
+  lib,
+  config,
+  inputs,
+  ...
+}:
 
 with lib;
 with lib.metacfg;