fix homeConfiguration errors and add recipe for home-manager

home/extra/nix.nix

@@ -0,0 +1,46 @@
+{
+  outputs,
+  lib,
+  pkgs,
+  inputs,
+  ...
+}:
+{
+  config = {
+    nixpkgs = {
+      config = {
+        allowUnfree = true;
+        allowUnfreePredicate = (_: true);
+      };
+      overlays = [
+        outputs.overlays.modifications
+        outputs.overlays.additions
+      ];
+    };
+    nix = {
+      package = pkgs.nix;
+      settings = {
+        inherit (outputs.nix.settings) substituters;
+        trusted-public-keys = [
+          "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+          "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
+          "cosmic.cachix.org-1:Dya9IyXD4xdBehWjrkPv6rtxpmMdRel02smYzA85dPE="
+        ];
+        auto-optimise-store = lib.mkDefault true;
+        experimental-features = [
+          "nix-command"
+          "flakes"
+        ];
+        warn-dirty = false;
+        use-xdg-base-directories = true;
+      };
+      registry.home = lib.mkDefault {
+        from = {
+          type = "indirect";
+          id = "home";
+        };
+        flake = inputs.nixpkgs;
+      };
+    };
+  };
+}