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-plugin

@@ -28,7 +28,7 @@ rows=$(jq -r --arg icon "$PLUGIN_ICON" \
   ". as \$plugins
    | .[] | select($filter)
    | \$icon + \"\\t\" + .name + \"\\t\" + .id" <<<"$plugins")
-[[ -n $rows ]] || { omarchy-notification-send "No plugin to ${1}"; exit 0; }
+[[ -n $rows ]] || { omarchy-notification-send "$(omarchy-text "No plugin to $1")"; exit 0; }
 
 selection=$(omarchy-menu-select "${1^} plugin" <<<"$rows") || exit 0
 [[ -n $selection ]] || exit 0