Give the landing page a minimal identity and reactive GSAP background

[dskvr]

Redesign the root landing page after #38 with a coherent visual identity and a compact product composition.

Acceptance:

• Remove needless panels, borders, corner rounding, shadows, glows, pill buttons and backend capability cards.
• Establish a deliberate logo/font/color/layout language; integrate the product screenshot in the main composition.
• Use GSAP for a restrained background that reacts to pointer motion and clicks, changes color with install tabs, and acknowledges successful copy actions.
• Preserve every installation command, accessible tabs, clipboard handling, no-JavaScript fallback and metadata from Make platform installation the homepage default #38.
• Respect reduced motion and keep animation bounded/paused when hidden.
• Open a PR with embedded desktop/mobile and interaction-state screenshot proofs.

Layers: website/UI only, plus documentation and tests. Explicitly requested dependency: GSAP, version checked and pinned. Validation: existing homepage regression suite plus animation/accessibility checks, responsive screenshots, static-site checks, typecheck/test/build. Audio, installer and distro packages are unchanged.