docs(site): build the landing page with GSAP scroll scenes

[hyamero]

Builds the landing page (spec build steps 3 to 5). Stacked on the static-pages PR; merge that one first.

• The canvas's desktop (1440 × 900) and phone (390 × 844) compositions. Each scene pins and scrubs its own GSAP timeline with ScrollTrigger, inside gsap.matchMedia.
• The canvas's timings, converted to GSAP percentage keyframes, with the canvas's eases passed through CustomEase.
• With reduced motion or no JavaScript, every scene shows its finished frame.
• Real diagrams only:
  • The "lights on" scene drops the real demo layout onto the map, then hands over to the live viewer.
  • The "five kinds" scene lays out one checkout drawn as each kind, and generates its card slots and timelines from those layouts.
• Static diagrams are rendered to HTML at build time, so pages ship none of the viewer's diagram code for them. The landing scores 91 on Lighthouse performance (65 before).
• Adds Playwright smoke tests for every route, the resting frames, the phone composition and the viewer island. The CI site job runs them against the production build.

[vercel]

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Project	Deployment	Actions	Updated
stackmap-site	Ready	Preview	Sep 30, 2026 2:31pm UTC

[github-actions]

🎉 This PR is included in version 0.1.0-rc.1 🎉

The release is available on:

• v0.1.0-rc.1
• GitHub release

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[github-actions]

🎉 This PR is included in version 0.1.0 🎉

The release is available on:

• v0.1.0
• GitHub release

Your semantic-release bot 📦🚀