feat(capture): improve capture quality + clean up CLAUDE.md

Capture improvements:
- Font weights via document.fonts API + DOM sampling (variable font detection)
- Section background-image extraction (no more false #FFFFFF on hero photos)
- Detected libraries surfaced in CLAUDE.md brand summary
- Structured visible-text.txt with [tag] prefixes, cookie/nav noise filtered
- tokens.json cleaned: removed images/paragraphs/icons (duplicated elsewhere),
  filtered sections to heading-only, trimmed cssVariables to design-relevant
- Removed redundant scroll pass in htmlExtractor (2-5s faster per capture)
- Font cap at 20 families, Placeholder/Fallback fonts filtered

CLAUDE.md rewrite:
- Removed prescriptive tone ("use exact strings" → "rephrase freely")
- Removed fluff sections (How to Create, DESIGN.md warning, Example Prompts,
  Source Patterns)
- asset-descriptions.md promoted to first data row
- Removed assets-catalog.json from inventory

Skill fixes:
- Dead shader refs → point to packages/shader-transitions/README.md
- Google Fonts import in techniques.md → local @font-face placeholder
- Added Stripe DESIGN.md as light-brand example
- Removed HANDOFF.md generation from step-7
- Updated step-1 for new font weight + visible-text formats

skills/website-to-hyperframes/references/step-6-build.md

@@ -82,7 +82,7 @@ Every visible element must have continuous motion. A still image on a still back
 Check the storyboard's transition specification for this beat:
 
 - **CSS transition**: implement the exit animation (e.g., `y:-150, blur:30px, 0.33s power2.in`). The next composition handles its own entry.
-- **Shader transition**: no exit animation needed — the shader handles the blend. Read `skills/hyperframes/references/transitions/shader-setup.md` for the full WebGL boilerplate and `skills/hyperframes/references/transitions/shader-transitions.md` for the fragment shader. Copy the FULL boilerplate — a simplified version produces black screens.
+- **Shader transition**: no exit animation needed — the shader handles the blend. Read `packages/shader-transitions/README.md` for the API, available shaders, and setup. The package handles WebGL init, capture, and GSAP integration — do not copy raw GLSL manually.
 - **Hard cut**: no exit animation. The scene simply ends.
 
 For all CSS transition types and their GSAP implementations, read `skills/hyperframes/references/transitions/catalog.md`.