chore: move nix specific config to its own module

flake.nix

@@ -24,6 +24,7 @@
         ./modules/shell.nix
         ./modules/stow.nix
         ./modules/users.nix
+        ./modules/nix.nix
 
         ./modules/secureboot.nix
         lanzaboote.nixosModules.lanzaboote

hosts/nixos-common.nix

@@ -5,10 +5,6 @@
 { config, lib, pkgs, ... }:
 
 {
-
-  # Nix Configuration
-  nixpkgs.config.allowUnfree = true;
-
   # Use the systemd-boot EFI boot loader.
   boot.loader.systemd-boot.enable = true;
   boot.loader.efi.canTouchEfiVariables = true;
@@ -35,10 +31,6 @@
   networking.firewall.allowedTCPPorts = [ 22 ];
   # networking.firewall.allowedUDPPorts = [ ... ];
 
-  # Enable nix-command and flakes
-  nix.settings.experimental-features = [ "nix-command" "flakes" ];
-
-
   # This option defines the first version of NixOS you have installed on this particular machine, and is used
   # to maintain compatibility with application data (e.g. databases) created on older NixOS versions. Most
   # users should NEVER change this value after the initial install, for any reason, even if you've upgraded

modules/nix.nix

@@ -0,0 +1,9 @@
+{ config, lib, pkgs, ... }:
+
+{
+  # Nix Configuration
+  nixpkgs.config.allowUnfree = true;
+
+  # Enable nix-command and flakes
+  nix.settings.experimental-features = [ "nix-command" "flakes" ];
+}