Mirror manager: shellcheck fixes

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QKxGW1raAWaqeU8WdHsMsp

bin/omarchy-cn-mirror-apply

@@ -13,7 +13,8 @@ target="${1:?usage: omarchycn mirror apply <china|official|mirror-id>}"
 case "$target" in
 china)
   echo "Benchmarking China mirrors..."
-  mapfile -t ranked < <(cn_mirror_rank $(cn_mirror_ids_by_region cn))
+  mapfile -t cn_ids < <(cn_mirror_ids_by_region cn)
+  mapfile -t ranked < <(cn_mirror_rank "${cn_ids[@]}")
   if (( ${#ranked[@]} == 0 )); then
     echo "No healthy China mirror reachable; keeping current mirrorlist" >&2
     exit 1

cn/lib/mirror.sh

@@ -1,3 +1,4 @@
+# shellcheck shell=bash
 # Sourced helpers for omarchy-cn-mirror-* commands
 
 CN_MIRRORS_JSON="$OMARCHY_PATH/cn/mirrors.json"