system: move all to defaults

defaults/lix.nix

@@ -0,0 +1,33 @@
+{
+  pkgs,
+  lib,
+  config,
+  ...
+}:
+
+let
+  name = "lix";
+  cfg = config.nixowos.system.${name};
+in
+{
+  options.nixowos.system.${name} = {
+    enable = lib.mkEnableOption name;
+  };
+
+  config = lib.mkIf cfg.enable {
+    # use lix, a fork of nix
+    # see: https://lix.systems/about
+    nix.package = pkgs.lixPackageSets.stable.lix;
+    # overlays so that all nix tools use lix
+    nixpkgs.overlays = [
+      (final: prev: {
+        inherit (prev.lixPackageSets.stable)
+          nixpkgs-review
+          nix-eval-jobs
+          nix-fast-build
+          colmena
+          ;
+      })
+    ];
+  };
+}