feat(localization): add enable option

modules/localization/default.nix

@@ -1,6 +1,13 @@
-{ config, ... }:
+{ lib, config, ... }:
 
+let
+  cfg = config.localization;
+in
 {
+  options.localization.enable = lib.mkEnableOption "localization";
+
+  config = lib.mkIf cfg.enable {
     time.timeZone = config.host.timezone;
     i18n.defaultLocale = config.host.locale;
+  };
 }