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.

test/shell.d/sleep-lock-test.sh

@@ -18,6 +18,7 @@ setup_scenario() {
   notify_log="$scenario_dir/notifications"
   journal_log="$scenario_dir/journal"
   mkdir -p "$mock_bin" "$state_dir"
+  ln -s "$ROOT/bin/omarchy-text" "$mock_bin/omarchy-text"
   : >"$notify_log"
   : >"$journal_log"