fix: can't use nixpkgs.config and nixpkgs.pkgs at the same time, and other renames

lib/macosSystem.nix

@@ -17,7 +17,11 @@ in
       darwin-modules
       ++ [
         ({lib, ...}: {
-          nixpkgs.pkgs = import nixpkgs-darwin {inherit system;};
+          nixpkgs.pkgs = import nixpkgs-darwin {
+            inherit system; # refer the `system` parameter form outer scope recursively
+            # To use chrome, we need to allow the installation of non-free software
+            config.allowUnfree = true;
+          };
         })
       ]
       ++ (