add sane nix options

config.nix

@@ -86,6 +86,32 @@
     };
   };
 
+  nix = {
+    settings = {
+      substituters = lib.mkForce [
+        "https://cache.nixos.org"
+        "https://nix-community.cachix.org"
+      ];
+      trusted-public-keys = lib.mkForce [
+        "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
+        "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+      ];
+      sandbox = true;
+      require-sigs = true;
+      max-jobs = "auto";
+      allowed-users = [ "*" ];
+      trusted-users = [
+        "root"
+      ];
+      experimental-features = [
+        "nix-command"
+        "flakes"
+      ];
+      use-xdg-base-directories = true;
+    };
+    package = pkgs.lix;
+  };
+
   disko.devices = {
     disk = {
       main = {