hotfix: support ci package list on mac bash (r1)

[RyshMan]

Problem

• post-merge main CI failed in the ci workflow on macos-latest
• the new Go coverage package-list step used mapfile, which is unavailable in the Bash version on GitHub's macOS runners
• that caused the package array to stay empty and go test to run against . instead of the filtered package set

Changes

• replace mapfile with a Bash 3.2-compatible while read array population loop in the ci workflow
• apply the same package-loading pattern to the matching nightly Windows workflow step so the coverage logic stays consistent

Validation

• make prepush-full
• git push -u origin codex/hotfix-ci-package-list-r1 (pre-push hook ran make prepush)