feat(x): add enable option

modules/x/default.nix

@@ -1,4 +1,9 @@
+{ lib, config, ... }:
+
 {
+  options.desktop.x.enable = lib.mkEnableOption "xmonad desktop";
+
+  config = lib.mkIf config.desktop.x.enable {
     services.xserver.windowManager.xmonad = {
       enable = true;
       enableContribAndExtras = true;
@@ -10,4 +15,5 @@
       xkb.layout = "us";
       xkb.variant = "";
     };
+  };
 }