Add Simplified Chinese as a system language

The installer asks for the language before the keyboard, and
Setup > Language (omarchy language en|zh) switches it later. Under
zh_CN the menu reads its labels from omarchy-menu.zh-cn.jsonc, the
shell from I18nZh.js through I18n.tr, and notifications are worded
by their sender through omarchy-text, which reads the same table.
User text is never translated.

bin/omarchy-menu-timezone

@@ -9,4 +9,4 @@ set -e
 timezone=$(timedatectl list-timezones | omarchy-menu-select "Set timezone" -- --width 520 --maxheight 520) || exit 1
 sudo timedatectl set-timezone "$timezone"
 omarchy-shell -q omarchy.clock refresh
-omarchy-notification-send "Timezone is now set to $timezone"
+omarchy-notification-send "$(omarchy-text "Timezone is now set to %1" "$timezone")"