docs: Restructure README for clarity and engagement

- Reduced from 832 lines to 104 lines
- Lead with value prop: "AI that predicts problems before they happen"
- Clear CTAs: Star, Discussions, Book, Docs
- Focused comparison table
- Quick install prominently featured
- Detailed docs moved to docs/ folder

Optimized for HN/Reddit readability.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: silversurfer562