Add sound effects and Void Hunt minigame

- Add Web Audio API sound engine with procedural sounds
- Add sounds for: pet, feed, spawn, achievement, purchase, release
- Add mute toggle button
- Add Void Hunt minigame (30s click target game)
- Award 5 Void Essence per target caught
- Persist mute state to localStorage

WORKLOG.md

@@ -48,10 +48,14 @@ A whimsical pocket dimension where digital companions called "Voidlings" float a
 - Added 2 new voidling types: Glitch (rare green) and Crystal (rare blue)
 - Added "Void Tycoon" achievement for accumulating 500 Void Essence
 - Updated biodiversity achievement to require all 6 voidling types
+- Added sound effects system using Web Audio API (pet, feed, spawn, achievement, purchase, release)
+- Added mute toggle button to control sounds
+- Added Void Hunt minigame - click targets for 30 seconds to earn Void Essence
 
 ### Next Steps
-1. Add sound effects
-2. Add voidling minigames
+1. Add more minigames
+2. Add voidling evolution/combat system
+3. Add decorations for the chamber
 
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