misc improvements to modularity

modules/features/applications/cli/fastfetch.nix

@@ -5,7 +5,7 @@
 
   flake.nixosModules.global = { pkgs, lib, config, ... }: {
     config = lib.mkIf (config.features.applications.cli.fastfetch.enable) (inputs.helpers.mkIfElse (config.features.nixos.home-manager.enable) {
-      home-manager.users.grey.features.applications.cli.fastfetch.enable = lib.mkDefault true;
+      home-manager.users.${config.info.userName}.features.applications.cli.fastfetch.enable = lib.mkDefault true;
     } {
       environment.systemPackages = [ pkgs.fastfetch ];
     });