✨ feat(region): default china installs to Asia/Shanghai

- ✨ offline China first boots preselect `Asia/Shanghai` from the region profile instead of the top of the list
- 📝 profiles may name a `timezone`; first-boot setup reads it for the region in `/etc/omarchy/region`

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SdXqTwm63rRMwotZ1xqLC8

test/shell.d/region-timezone-test.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+
+set -euo pipefail
+source "$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)/base-test.sh"
+
+scratch=$(mktemp -d)
+trap 'rm -rf "$scratch"' EXIT
+
+zone=$(<"$ROOT/default/regions/cn/timezone")
+[[ $zone == "Asia/Shanghai" ]] || fail "China profile names Asia/Shanghai"
+[[ -f /usr/share/zoneinfo/$zone ]] || fail "China profile timezone exists in tzdata"
+pass "China profile defaults to an existing Asia/Shanghai zone"
+
+# Load the real region_timezone() from the first-boot command.
+OMARCHY_PATH="$ROOT"
+REGION_MARKER="$scratch/region"
+eval "$(sed -n '/^region_timezone() {/,/^}/p' "$ROOT/bin/omarchy-provision-owner")"
+
+[[ -z $(region_timezone) ]] || fail "missing region marker offers no timezone"
+for region in global CN ../cn zz ""; do
+  printf '%s\n' "$region" >"$REGION_MARKER"
+  [[ -z $(region_timezone) ]] || fail "region '$region' offers no timezone"
+done
+pass "global, unknown, and malformed regions offer no timezone"
+
+printf 'cn\n' >"$REGION_MARKER"
+[[ $(region_timezone) == "Asia/Shanghai" ]] || fail "cn region offers Asia/Shanghai"
+pass "cn region offers its profile timezone"
+
+grep -qF 'omarchy_prompt_timezone "$(region_timezone)"' "$ROOT/bin/omarchy-provision-owner" ||
+  fail "first-boot setup passes the region timezone to the prompt"
+pass "first-boot setup preselects the region timezone"