* fix(nightly): pick latest nightly by published_at
GitHub's /releases endpoint is not reliably ordered by published_at,
so resolveNightly could pick an older nightly than the most recent
one. Filter, sort by published_at desc, and take the first.
* test(nightly): add regression coverage for release ordering
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
