Extract configuration to own module

modules/common-system.nix

@@ -1,5 +1,6 @@
-{config, pkgs, inputs, ...}:
-{
+{ config, pkgs, inputs, ... }: {
+  imports = [ ./nix-config.nix ];
+
   i18n.defaultLocale = "en_US.UTF-8";
   time.timeZone = "Europe/Berlin";
 
@@ -21,25 +22,9 @@
   networking.firewall.enable = true;
 
   nix = {
-      gc = {
-        automatic = true;
-        dates = "weekly";
-        options = "--delete-older-than 30d";
-      };
-
-      registry = {
-        nixpkgs.flake = inputs.nixpkgs;
-        nixpkgs-unstable.flake = inputs.nixpkgs-unstable;
-      };
-
-      settings = {
-        auto-optimise-store = true;
-        experimental-features = [ "nix-command" "flakes" ];
-        warn-dirty = false;
-
-        # avoid unwanted garbage collection when using direnv
-        keep-outputs = true;
-        keep-derivations = true;
-      };
+    registry = {
+      nixpkgs.flake = inputs.nixpkgs;
+      nixpkgs-unstable.flake = inputs.nixpkgs-unstable;
+    };
   };
 }