【v2.4.2】Added Music Player

[h2]Update Notes:[/h2]

• Added BGM Music Player, which unlocks songs as you progress through the game.
  
• Changed the unlock level for 【Beach Brawl: Swimsuits vs. Oni Chaos Event】 to 4-5 (right after the player unlocks Sanbi No Kitsune).
  
• Fixed minor bugs.