Rename network.nix to network-client.nix

It contains setting up NetworkManager which is not needed for servers

hosts/julius-framework/default.nix

@@ -8,10 +8,9 @@
   imports =
     [
       ../../modules/nix.nix
-      ../../modules/system.nix
       ../../modules/firmware.nix
       ../../modules/laptop.nix
-      ../../modules/network.nix
+      ../../modules/network-client.nix
       ../../modules/locale.nix
       ../../modules/timezone-imperatively.nix
       ../../modules/boot-login.nix

modules/system.nix

@@ -1,23 +0,0 @@
-{
-  pkgs,
-  lib,
-  username,
-  ...
-}: {
-  # do garbage collection weekly to keep disk usage low
-  nix = {
-    settings = {
-      experimental-features = ["nix-command" "flakes"];
-    };
-
-    gc = {
-      automatic = lib.mkDefault true;
-      dates = lib.mkDefault "weekly";
-      options = lib.mkDefault "--delete-older-than 7d";
-    };
-  };
-
-  # Allow unfree packages
-  nixpkgs.config.allowUnfree = true;
-
-}