Add ambient music

[jeffbulltech]

• Integrate a background music/ambiance player that players can toggle on/off during a campaign session
• Provide curated ambient tracks/loops matched to context (exploration, combat, tavern, dungeon) with smooth crossfade transitions
• Let the AI GM or scene triggers suggest/switch ambiance based on narrative context (e.g., entering combat, exploring a dungeon)
• Add player controls for volume, mute, and track selection, independent of voice narration audio
• Support per-campaign or per-user music preferences, persisted across sessions
• Ensure ambient tracks are royalty-free or properly licensed to avoid IP issues