refactor: simplify README for broader audience

Redesigned README to:
- Start with clear benefits (not technical details)
- Explain WHAT is WARP and WHY it's useful
- Use simple language for non-technical users
- Show 30-second quick start
- Move technical details to sub-pages (DETAILS.md, etc.)
- Add comparison table: Official App vs warp-cli
- Include basic FAQs addressing common questions
- Links to appropriate docs for different audiences

Now targets:
- New users (brief intro, quick setup)
- Developers (scripts, automation, examples)
- Technical users (architecture, system details)

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

Author: ashu17706