restructure system configuration

system/modules/nix/default.nix

@@ -0,0 +1,8 @@
+{
+  imports = [
+    ./nh.nix
+    ./nix.nix
+    ./nixpkgs
+    ./subs.nix
+  ];
+}

system/modules/nix/nh.nix

@@ -0,0 +1,16 @@
+{ inputs, ... }: {
+
+  imports = [
+    inputs.nh.nixosModules.default
+  ];
+
+  environment.variables.FLAKE = "/home/ooks/Coding/nix/ooks-io/nix";
+
+  nh = {
+    enable = true;
+    clean = {
+      enable = true;
+      extraArgs = "--keep-since 30d";
+    };
+  };
+}

system/modules/nix/nix.nix

@@ -0,0 +1,15 @@
+{ config, lib, pkgs, inputs, ... }: {
+
+  nix = {
+    settings = {
+      trusted-users = [ "root" "@wheel" ];
+      auto-optimise-store = lib.mkDefault true;
+      experimental-features = [ "nix-command" "flakes" "repl-flake" ];
+      warn-dirty = false;
+      system-features = [ "kvm" "big-parallel" "nixos-test" ];
+      flake-registry = "";
+    };
+    registry = lib.mapAttrs (_: value: { flake = value; }) inputs;
+    nixPath = [ "nixpkgs=${inputs.nixpkgs.outPath}" ];
+  }; 
+}

system/modules/nix/nixpkgs.nix

@@ -0,0 +1,13 @@
+{ outputs, ... }: {
+
+  nixpkgs = {
+    overlays = builtins.attrValues outputs.overlays;
+    config = {
+      allowUnfree = true;
+      permittedInsecurePackages = [
+        "openssl-1.1.1u"
+        "electron-25.9.0"
+      ];
+    };
+  };
+}

system/modules/nix/subs.nix

@@ -0,0 +1,18 @@
+{
+  nix.settings = {
+    substituters = [
+      "https://cache.nixos.org?priority=10"
+      "https://fufexan.cachix.org"
+      "https://helix.cachix.org"
+      "https://hyprland.cachix.org"
+      "https://nix-community.cachix.org"
+    ];
+
+    trusted-public-keys = [
+      "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
+      "helix.cachix.org-1:ejp9KQpR1FBI2onstMQ34yogDm4OgU2ru6lIwPvuCVs="
+      "hyprland.cachix.org-1:a7pgxzMz7+chwVL3/pzj6jIBMioiJM7ypFP8PwtkuGc="
+      "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+    ];
+  };
+}