Audio system: music, SFX, crossfades, per-scene cues
AudioManager now loads all SFX + music from Resources/Audio at boot,
AudioManager now loads all SFX + music from Resources/Audio at boot, handles scene-specific music (menu theme, combat, rest, shop, boss, act-specific map themes, victory fanfare), crossfades between tracks, and persists volume settings via PlayerPrefs.
Commit fcf713f by astafford8488.