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.

shell/plugins/services/media/Service.qml

@@ -411,7 +411,7 @@ Item {
         handled = true
       }
     } else if (action === "playPause") {
-      actionLabel = player && player.isPlaying ? "Pause" : "Play"
+      actionLabel = player && player.isPlaying ? I18n.tr("Pause") : I18n.tr("Play")
       iconName = player && player.isPlaying ? "media-pause" : "media-play"
       if (player && player.isPlaying && player.canPause) {
         player.pause()