all application options will adapt to environment

when used either with nixos (no home-manager) or home-manager standalone, `features.applications.<name>.enable` options still perform some functionality, rather than assuming a full nixos + home-manager setup like before

modules/features/applications/gui/kitty.nix

@@ -8,11 +8,7 @@
         (mkIf (!p) no)
       ];
     in lib.mkIf (config.features.applications.gui.kitty.enable) (mkIfElse (config.features.nixos.home-manager.enable) {
-      home-manager.sharedModules = [
-        {
-          features.applications.gui.kitty.enable = lib.mkDefault true;
-        }
-      ];
+      home-manager.users.grey.features.applications.gui.kitty.enable = lib.mkDefault true;
     } {
       environment.systemPackages = [ pkgs.kitty ];
     });