Learner Engine 2.0 pilot for batnhatamkinhdehieu

Optional route: /hoc-hom-nay/.

This is a separate opt-in learning prototype, not a replacement for the production learner progress, quizzes or private journal.

It uses localStorage key factory-learning-pilot-v2:bat_nha_tam_kinh and does not write to existing application keys. Never copy personal journal text or secrets into TTS or telemetry.

Pilot assessment is self reported. No independent grading, no actual 7-day retention effect or application Skill Lift has been measured.

Run static smoke: node qa/learning-pilot.cjs. Run browser: node qa/learning-pilot-browser.cjs (requires Playwright Chromium, installed in CI). The canonical implementation lives at phanminhtuandalat/topic-learning-site-factory and is copied into assets/learning-engine/ as an immutable adapter snapshot. Rollback: revert this PR, preserving user progress in original storage key.