feat: layered sticker construction with per-layer materials

[jal-co]

What

Rebuilds the sticker as its real production stack when Layers is enabled (now the default):

• Backing: the kiss-cut silhouette from the liner side, matte paper white
• Kiss-cut: the die-cut shape in bare foil, no ink
• Artwork: the original image printed alone

Each layer has a material picker (Holo foil / Glitter / Chrome / Matte / Prism / Satin) via per-layer uniform overrides, plus a Thickness slider.

How

• Layers share the peel geometry and are lifted along the surface normal in the vertex shader (uLift), so the stack flips correctly on the peel flap - the liner shows, not the artwork through the back
• uBackStyle renders each layer's own texture/material on its back face; the flap underside is the backing liner
• New defaults: layers on, triangle overlay, 39% peel (from the reviewed settings JSON)

Testing

• tsc + build clean
• Visual: peel at multiple amounts/directions, tilt parallax, material presets per layer, GIF/PNG export unaffected (rebased on the export-crop fix)

[vercel]

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Project	Deployment	Actions	Updated (UTC)
holosticker	Ready	Preview	Aug 3, 2026 4:57pm