Add creative visual effects for mood emoji selection

[danielchalmers]

Adds 1.5-second animated visual effects when selecting mood emojis. Each emotion triggers a unique, creative particle animation that covers the entire viewport with random positioning.

Key features:
✅ Full viewport coverage with random positioning across entire screen
✅ 1.5-second animations for dramatic, expressive effects
✅ Completely unique, creative effects for every emoji (including neutral and thinking)
✅ Multiple particle types and secondary effects for visual richness
✅ Non-blocking - effects don't interfere with page interaction