Add common hosts config

hosts/common/global/nix.nix

@@ -0,0 +1,49 @@
+{
+  lib,
+  ...
+}:
+{
+  nix.settings.auto-optimise-store = lib.mkDefault true;
+  nix.settings.experimental-features = [
+    "nix-command"
+    "flakes"
+    "ca-derivations"
+  ];
+  # warn-dirty = false;
+
+  # Setup binary caches
+  nix.settings = {
+    substituters = [
+      "https://nix-community.cachix.org"
+      "https://cache.nixos.org/"
+      "https://hyprland.cachix.org"
+      "http://binarycache.julian-mutter.de"
+    ];
+    trusted-public-keys = [
+      "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+      "hyprland.cachix.org-1:a7pgxzMz7+chwVL3/pzj6jIBMioiJM7ypFP8PwtkuGc="
+      "binarycache.julian-mutter.de:oJ67uRFwRhNPKL58CHzy3QQLv38Kx7OA1K+6xlEPu7E="
+    ];
+
+    trusted-users = [
+      "root"
+      "@wheel"
+    ]; # needed for devenv to add custom caches
+  };
+
+  nix.gc = {
+    automatic = true;
+    dates = "weekly";
+    # Keep the last 3 generations
+    options = "--delete-older-than +3";
+  };
+
+  programs.nix-ld.enable = true;
+
+  # TODO: is this useful?, what does it do?
+  # nix.settings.flake-registry = ""; # Disable global flake registry
+  # Add each flake input as a registry and nix_path
+  # registry = lib.mapAttrs (_: flake: { inherit flake; }) flakeInputs;
+  # nixPath = lib.mapAttrsToList (n: _: "${n}=flake:${n}") flakeInputs;
+
+}