feat: pooled laminate flare structure - #7

What

Richer holofoil material, keeping Holosticker's rainbow palette:

• Pooled flare zones: film intensity pools across the surface via domain-warped fbm - broad sweeps flowing over calm foil instead of uniform banding
• Two-layer laminate: metallic base reflections tinted by the ink color, with the rainbow flare compositing above the print so it stays vivid over dark ink
• Curl-driven shift: the peel's curvature phases the rainbow, so the flap sweeps hues
• Glitter twinkle: per-cell micro-facets that light up as the view angle sweeps

Credit

The layering/pooling concept is inspired by the konvert.design sticker tool (credited in the shader source). Their thin-film physics and light rig were evaluated and intentionally not used - colors and lighting remain Holosticker's own, and the implementation constants/structure are ours.

Testing

• tsc + build clean
• Visual: tilt sweep, peel, all three patterns, overlays on/off, layers on/off