### Description Create the core domain model classes. Requirements covered: Architecture: Player, Song, Question, AnswerSubmission, Leaderboard, GameSession Acceptance criteria: Player (name, score, id) Song (title, artist, previewUrl) Question (song, answer options, correct answer) AnswerSubmission (playerId, answer, timestamp) LeaderboardEntry (playerId, name, score) GameSession (pin, players, rounds, currentRound, state) ### Related requirement _No response_ ### Architecture layer None