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/panels/elsewhen/CityMatches.qml

@@ -73,7 +73,7 @@ Column {
     width: parent.width
     horizontalAlignment: Text.AlignHCenter
     topPadding: Style.spacing.md
-    text: list.citySearch.loading ? list.citySearch.loadingText : "No matches"
+    text: list.citySearch.loading ? list.citySearch.loadingText : I18n.tr("No matches")
     color: list.citySearch.fainter
   }