- Connection pool and a small migration runner (schema_migrations, one
transaction per migration, advisory lock)
- games and game_players tables with indexes for a user's games and for
popular games
- PostgresGameHistoryRepository: idempotent save, get, recent games of a
user, popular games
- Integration tests against a real Postgres via testcontainers; a custom
Jest environment gives tests Node's web globals, which Jest 27 leaves out
- GameRecord carries the number of distinct spectators
