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-theme-bg-intro

@@ -10,12 +10,12 @@ toggle="$HOME/.local/state/omarchy/toggles/background-intros-off"
 case ${1:-} in
   enable)
     rm -f "$toggle"
-    omarchy-notification-send "Background Intros" "Enabled"
+    omarchy-notification-send "$(omarchy-text "Background Intros")" "$(omarchy-text "Enabled")"
     ;;
   disable)
     mkdir -p "$(dirname "$toggle")"
     touch "$toggle"
-    omarchy-notification-send "Background Intros" "Disabled"
+    omarchy-notification-send "$(omarchy-text "Background Intros")" "$(omarchy-text "Disabled")"
     ;;
   toggle)
     if [[ -f $toggle ]]; then