[desktop] Refactor into multiple components

roles/desktop/gaming.nix

@@ -0,0 +1,17 @@
+{ lib, config, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.roles.desktop;
+in
+{
+  config = mkIf (cfg.enable && cfg.gaming) {
+    environment.systemPackages = with pkgs; [
+      steam
+      lutris
+    ];
+
+    # Possibly other gaming specific services or settings
+  };
+}