The readme-sync workflow no longer fails when README.md and
README_TW.md don't change together. Instead, check_readme_sync.py
reports drift: it lists commits that touched README.md after the
last README_TW.md update, plus the pending English diff to translate
and backfill. CI surfaces drift as a warning annotation only.
Claude-Session: https://claude.ai/code/session_01PG9Pz6tcUfgpTHLjq3BT5Q