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-system-shutdown

@@ -7,7 +7,7 @@
 if [[ ${1:-} == "--inhibited" ]]; then
   # Close windows in the background so they cannot delay power-off.
   (
-    omarchy-osd -i shutdown -m "Shutting down" -d 5000
+    omarchy-osd -i shutdown -m "$(omarchy-text "Shutting down")" -d 5000
     omarchy-state clear re*-required
     omarchy-hyprland-window-close-all
   ) &
@@ -21,7 +21,7 @@ elif [[ ${1:-} == "--inhibit" ]]; then
     --who=Omarchy --why="Shutdown in progress" --mode=block \
     "$0" --inhibited || {
     status=$?
-    omarchy-notification-send -u critical "Shutdown failed" "Could not complete shutdown. Please try again."
+    omarchy-notification-send -u critical "$(omarchy-text "Shutdown failed")" "$(omarchy-text "Could not complete shutdown. Please try again.")"
     exit "$status"
   }
 else