feat(landing): Complete redesign with scroll-based storytelling

- Remove bland 'Powered by' section
- Add scroll-based story flow with animations
- 'The Problem' section: grep chaos terminal visualization
- 'The Solution' section: CodeIntel clean result demo
- 'How It Works' section: 3-step process
- 'Features' section: MCP, Speed, Intelligence, Open Source
- Final CTA with GitHub star button
- IntersectionObserver for fade-in animations
- Cleaner visual hierarchy and spacing

Part of landing page redesign (#22)

Author: DevanshuNEU