New core module: juice.js
- Particle burst engine (coins, stars, confetti, squares)
- Coin fly-to-target animation (particles arc from source to HUD)
- Screen shake with intensity decay
- Number counter with eased tick-up
- Haptic feedback (light/medium/heavy/success/error patterns)
- Element glow/pulse effects
- Slam-in, bounce-in, slide-up-bounce animations
- Stagger utility for sequential element animations
- Float/breathe idle animations
- Full-screen flash effect

CSS juice system:
- 16 keyframe animations (slamIn, slideUpBounce, breatheGlow, ringExpand, wobble, numberPop, shimmerBorder, bgGradientMove...)
- Ambient moving gradient background on body
- Primary buttons breathe with golden glow when idle
- Scene transitions: spring overshoot (scale 0.88→1.02→1)
- will-change hints on interactive elements

Home screen juiced:
- Game tiles bounce-in staggered on load
- Tiles float with subtle Y-axis bob (different speeds)
- Tile press: haptic + pulse glow
- Game menu slams up with spring overshoot

Result screen juiced:
- Screen flash (green for win, red for loss)
- Trophy/skull slams in with 1.8x scale overshoot
- Rating counter ticks up/down per digit
- Win: confetti burst (40 particles) + haptic success
- Loss: screen shake + haptic error
- Coins fly from result area to HUD counter
- Buttons stagger slide-up on entry
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>