- Add Better Auth config with Google + GitHub social providers
- Mount auth handler on /api/auth/* in Express
- Generate and migrate auth tables (user, session, account, verification)
- Deduplicate term_glosses data for tighter unique constraint
- Drop legacy users table
Add the session storage infrastructure for tracking correct answers
during a game. Designed for easy swap to Valkey in Phase 4.
- GameSessionStore interface with create/get/delete methods, all async
to match the eventual Valkey implementation
- InMemoryGameSessionStore backed by a Map
- GameSessionData holds only the answer key (questionId → correctOptionId)
- Also fix root build script to build packages in dependency order
