Merge cn-region-switch (with omarchy #13690)

# Conflicts:
#	AGENTS.md
#	bin/omarchy-refresh-pacman
#	default/omarchy/omarchy-menu.jsonc
#	install/post-install/pacman.sh
#	shell/plugins/menu/MenuModel.js
#	test/shell.d/menu-test.sh

manual/02-getting-started.md

@@ -20,6 +20,10 @@ Now you're ready to Omarchy!
 
 The full-disk encryption won't allow you to enter the password from a Bluetooth keyboard at startup. Just like you can't use a Bluetooth keyboard to enter the BIOS on a PC. You'll need a keyboard that either uses a 2.4ghz dongle or a cable (which is much nicer for latency anyway!). I personally love the [Lofree Flow84](https://www.lofree.co/products/lofree-flow-the-smoothest-mechanical-keyboard)!
 
+### Installing in China
+
+The timezone you pick in the installer decides the region: `Asia/Shanghai` brings Chinese package and developer mirrors and the China apps. See [China](52-china.md).
+
 ### Installing for another owner
 
 If you're setting up a machine for someone else — a family member, a new employee, a buyer — you shouldn't be answering the personal questions on their behalf. Hit `Ctrl + C` on the very first screen of the installer (the language and keyboard selection), and Omarchy will offer to prepare the machine for another owner instead. The system installs right away, but all the personal setup — keyboard layout, username, password — is deferred until the machine boots for the first time. The drive is still encrypted by default, and the password the new owner picks on that first boot becomes the encryption password too. (A machine you've already been using can be handed over without a reinstall too — see [resetting the computer](48-security.md).)