Add a Setup > Region toggle with Chinese language and input method

`omarchy region china` switches the system language to zh_CN, installs the
Rime Ice input method through Andy Stewart's rime-ice-installer, makes Rime
the default with Ctrl+Space as the toggle, and swaps the Omarchy menu to
Chinese labels through the user-extension overlay; `omarchy region world`
puts the language and menu back and leaves the input method installed.
mergeMenuSources now only overrides the fields an extension declares, as
docs/menu.md documents, which the label-only overlay needs.

Co-authored-by: Andy Stewart <lazycat.manatee@gmail.com>

test/shell.d/region-test.sh

@@ -0,0 +1,105 @@
+#!/bin/bash
+
+set -euo pipefail
+
+source "$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)/base-test.sh"
+
+test_tmp=$(mktemp -d)
+trap 'rm -rf "$test_tmp"' EXIT
+
+mock_bin="$test_tmp/bin"
+test_home="$test_tmp/home"
+pkg_log="$test_tmp/pkg-add"
+installer_log="$test_tmp/installer"
+sudo_log="$test_tmp/sudo"
+systemctl_log="$test_tmp/systemctl"
+mkdir -p "$mock_bin" "$test_home"
+
+cat >"$mock_bin/omarchy-pkg-add" <<'SH'
+#!/bin/bash
+printf '%s\n' "$*" >>"$OMARCHY_TEST_PKG_LOG"
+SH
+
+cat >"$mock_bin/sudo" <<'SH'
+#!/bin/bash
+printf '%s\n' "$*" >>"$OMARCHY_TEST_SUDO_LOG"
+SH
+
+cat >"$mock_bin/systemctl" <<'SH'
+#!/bin/bash
+printf '%s\n' "$*" >>"$OMARCHY_TEST_SYSTEMCTL_LOG"
+SH
+
+cat >"$mock_bin/rime-ice-installer" <<'SH'
+#!/bin/bash
+printf 'ran\n' >>"$OMARCHY_TEST_INSTALLER_LOG"
+mkdir -p "$HOME/.local/share/fcitx5/rime"
+touch "$HOME/.local/share/fcitx5/rime/rime_ice.schema.yaml"
+SH
+
+chmod +x "$mock_bin"/*
+
+export HOME="$test_home"
+export PATH="$mock_bin:$ROOT/bin:$PATH"
+export OMARCHY_TEST_PKG_LOG="$pkg_log"
+export OMARCHY_TEST_INSTALLER_LOG="$installer_log"
+export OMARCHY_TEST_SUDO_LOG="$sudo_log"
+export OMARCHY_TEST_SYSTEMCTL_LOG="$systemctl_log"
+export OMARCHY_PATH="$ROOT"
+
+[[ $(omarchy-region) == "World" ]] || fail "region defaults to World before any choice"
+pass "region defaults to World before any choice"
+
+mkdir -p "$test_home/.config/omarchy/extensions"
+cp "$ROOT/config/omarchy/extensions/omarchy-menu.jsonc" "$test_home/.config/omarchy/extensions/omarchy-menu.jsonc"
+
+omarchy-region china >/dev/null
+cmp -s "$ROOT/default/omarchy/omarchy-menu.zh-cn.jsonc" "$test_home/.config/omarchy/extensions/omarchy-menu.jsonc" ||
+  fail "china installs the Chinese menu labels over the stock sample"
+grep -q "locale-gen" "$sudo_log" || fail "china generates the Chinese locale"
+grep -Fx "localectl set-locale LANG=zh_CN.UTF-8" "$sudo_log" >/dev/null || fail "china sets the system language"
+grep -Fx "pacman -Sy" "$sudo_log" >/dev/null || fail "china syncs the repo databases before installing"
+grep -Fx "rime-ice-installer" "$pkg_log" >/dev/null || fail "china installs the Rime Ice installer package"
+(( $(wc -l <"$installer_log") == 1 )) || fail "china runs the Rime Ice installer"
+grep -A1 '^\[Groups/0/Items/0\]$' "$test_home/.config/fcitx5/profile" | grep -qFx "Name=rime" ||
+  fail "china makes Rime the first input method"
+grep -qFx "DefaultIM=rime" "$test_home/.config/fcitx5/profile" || fail "china makes Rime the group default"
+grep -qFx "0=Control+space" "$test_home/.config/fcitx5/config" || fail "china pins the Ctrl+Space toggle"
+grep -Fx -- "--user restart omarchy-fcitx5.service" "$systemctl_log" >/dev/null ||
+  fail "china restarts fcitx5 with the new profile"
+[[ $(omarchy-region) == "China" ]] || fail "china is stored as the region"
+pass "china sets up the language, menu and input method"
+
+omarchy-region china >/dev/null
+(( $(wc -l <"$installer_log") == 1 )) || fail "reapplying china skips the installed input method"
+(( $(grep -cFx "pacman -Sy" "$sudo_log") == 1 )) || fail "reapplying china skips the database sync too"
+pass "reapplying china is idempotent and leaves the input method alone"
+
+omarchy-region world >/dev/null
+cmp -s "$ROOT/config/omarchy/extensions/omarchy-menu.jsonc" "$test_home/.config/omarchy/extensions/omarchy-menu.jsonc" ||
+  fail "world restores the sample menu extension"
+[[ $(omarchy-region) == "World" ]] || fail "world is stored as the region"
+[[ -f $test_home/.local/share/fcitx5/rime/rime_ice.schema.yaml ]] || fail "world leaves the input method installed"
+grep -qFx "DefaultIM=rime" "$test_home/.config/fcitx5/profile" || fail "world leaves the input method configured"
+pass "world restores the menu and keeps the input method"
+
+printf '{"apps": {"label":"Mine"}}\n' >"$test_home/.config/omarchy/extensions/omarchy-menu.jsonc"
+if omarchy-region china >/dev/null 2>"$test_tmp/refusal"; then
+  fail "china refuses a menu extension someone wrote by hand"
+fi
+grep -q "menu:" "$test_tmp/refusal" || fail "china names the menu extension it refuses to touch"
+[[ $(omarchy-region) == "World" ]] || fail "a refused china run keeps the region"
+pass "china refuses a hand-written menu extension"
+grep -Fx '{"apps": {"label":"Mine"}}' "$test_home/.config/omarchy/extensions/omarchy-menu.jsonc" >/dev/null ||
+  fail "a refused china run leaves the extension untouched"
+
+omarchy-region world >/dev/null
+grep -Fx '{"apps": {"label":"Mine"}}' "$test_home/.config/omarchy/extensions/omarchy-menu.jsonc" >/dev/null ||
+  fail "world leaves a menu extension someone wrote by hand"
+pass "world only restores the extension Omarchy wrote"
+
+if omarchy-region china unexpected >/dev/null 2>&1; then
+  fail "region rejects extra arguments"
+fi
+[[ $(omarchy-region) == "World" ]] || fail "extra arguments change nothing"
+pass "region rejects extra arguments"