Recreate ai.com landing experience

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What changed

• Replaced the placeholder screen with a responsive recreation of the supplied ai.com/start references.
• Added an animated CSS/SVG light-streak hero powered by Framer Motion.
• Added the expanding Sign up / Log in navigation, interactive start CTA, persistent cookie controls, mission and claim cards, and oversized footer.
• Added responsive and reduced-motion behavior, semantic controls, focus states, favicon, and project documentation.
• Removed the superseded TypeScript/Tailwind placeholder entry files and configs while preserving the repository's AI Studio metadata files.

Why

The repository previously contained an empty placeholder app. This implements the requested mobile-first UI, UX, and motion treatment from the supplied screenshots.

Validation

• npm run build
• Headless Chromium render at 390 × 717
• Verified cookie dismissal, menu open/close, section scrolling, responsive layout, and zero console errors