Added user setup

modules/nix/default.nix

@@ -0,0 +1,28 @@
+{ pkgs, config, lib, ... }:
+let
+  cfg = config.luj.nix;
+in
+with lib;
+{
+  options.luj.nix = {
+    enable = mkEnableOption "Enable nix experimental";
+  };
+
+  config = mkIf cfg.enable
+    {
+      nix = {
+        autoOptimiseStore = true;
+        allowedUsers = [ "julien" ];
+        gc = {
+          automatic = true;
+          dates = "daily";
+        };
+        package = pkgs.nixUnstable;
+        extraOptions = ''
+          experimental-features = nix-command flakes
+        '';
+      };
+
+
+    };
+}