add overlay to lock vscode version, git config into symlink

modules/global/nixos.nix

@@ -54,15 +54,21 @@
     };
 
     environment.systemPackages = with pkgs; [
-      git
       fzf
       jq
       busybox
       ethtool
       hyperfine
+      nixd
+      nixfmt
     ] ++ config.features.applications.extraPackages;
 
     programs = {
+      git = {
+        enable = true;
+        lfs.enable = true;
+      };
+
       nano = {
         enable = true;
         nanorc = ''