adapt config for use with standalone home-manager

modules/global/helpers.nix

@@ -1,5 +1,11 @@
 { inputs, self, ... }: {
   flake.nixosModules.global = { pkgs, config, lib, ... }: {
+    options.helpers = {
+      # nothing here yet
+    };
+  };
+
+  flake.homeModules.global = { pkgs, config, lib, ... }: {
     options.helpers = {
       mkSymlinkActivationScript = lib.mkOption {
         type = lib.types.functionTo lib.types.str;