Merge omacom/omarchy-iso#241: region from the timezone in one ISO

Drop our --region build, prepare-region.sh, region skel, the preselected
China timezone, the explicit region in the configurator's JSON, Rime
bundling and its pin.

configs/airootfs/root/configurator

@@ -91,13 +91,6 @@ OMARCHY_ZH+=(
   ["Everything will be overwritten. There is no recovery possible."]="磁盘上的一切都会被覆盖，无法恢复。"
   ["Confirm overwriting %s"]="确认覆盖 %s"
 )
-# China preselects the bundled cn profile's timezone when geo guessing fails.
-REGION_TIMEZONE="${REGION_TIMEZONE:-/usr/share/omarchy-iso/region/timezone}"
-region_timezone() {
-  if [[ $region == "cn" ]]; then
-    head -n 1 "$REGION_TIMEZONE"
-  fi
-}
 
 # Partition creation helpers, shared with test/partition-numbering-test.sh so
 # the numbering logic can be exercised without a real disk.
@@ -370,7 +363,7 @@ user_form() {
 
   omarchy_prompt_identity || return $?
   omarchy_prompt_hostname || return $?
-  omarchy_prompt_timezone "$(region_timezone)" || return $?
+  omarchy_prompt_timezone || return $?
 }
 
 # Returns 0 on confirmed account details, or as soon as the keyboard screen
@@ -390,19 +383,25 @@ user_step() {
       continue
     fi
 
+    # The timezone selects the region (mirrors and repositories), using the
+    # same lookup as the orchestrator. Global installs get no extra row.
+    region=$(cd /usr/share/omarchy-iso 2>/dev/null && python -m orchestrator.region "$timezone") || region="global"
+    region_row=""
+    if [[ $region != "global" ]]; then
+      region_row="\n$(omarchy_text Region),$region"
+    fi
+
     # Add manual padding since gum table -p doesn't respect padding
-    local skipped region_label=Global
+    local skipped
     skipped=$(omarchy_text "[Skipped]")
-    [[ $region == "cn" ]] && region_label=China
     echo -e "$(omarchy_text Field),$(omarchy_text Value)
 $(omarchy_text Username),$username
 $(omarchy_text Password),$(printf "%${#password}s" | tr ' ' '*')
 $(omarchy_text "Full name"),${full_name:-$skipped}
 $(omarchy_text "Email address"),${email_address:-$skipped}
 $(omarchy_text Hostname),$hostname
-$(omarchy_text Timezone),$timezone
-$(omarchy_text Keyboard),$keyboard
-$(omarchy_text Region),$(omarchy_text "$region_label")" |
+$(omarchy_text Timezone),$timezone$region_row
+$(omarchy_text Keyboard),$keyboard" |
       gum table -s "," -p | sed "s/^/${PADDING_LEFT_SPACES}/"
 
     echo
@@ -907,7 +906,6 @@ run_partition_execute() {
         "input_method": "${keyboard_input_method:-none}",
         "input_xkb_layout": "${keyboard_xkb_layout:-}",
         "mode": "protected",
-        "region": "$region",
         "target_mount": "/mnt",
         "boot": {
             "esp_mount": "$esp_mount_in_target",
@@ -1141,8 +1139,8 @@ select_installation() {
 
 defer_provisioning=false
 install_target="full_disk"
-# A rerun arrives with the region chosen; otherwise the ISO's default.
-region="${OMARCHY_INSTALL_REGION:-$(<"${ISO_REGION_FILE:-/root/omarchy_region}")}"
+# A rerun arrives with the console language chosen; otherwise Global.
+region="${OMARCHY_INSTALL_REGION:-global}"
 
 # Let the live VT reach its settled width before the first screen so the logo
 # isn't measured against the transient 80-column boot console.
@@ -1256,7 +1254,6 @@ cat <<-_EOF_ >user_configuration.json
         "input_method": "${keyboard_input_method:-none}",
         "input_xkb_layout": "${keyboard_xkb_layout:-}",
         "mode": "full_disk",
-        "region": "$region",
         "defer_provisioning": $defer_provisioning,
         "target_mount": "/mnt",
         "boot": {