docs: Rewrite README with unified documentation voice

Completely rewrote README to match the warm, welcoming voice of the
comprehensive documentation, making it feel like one unified project.

Key changes:

Voice & Tone:
- Changed from formal/technical to warm and approachable
- Made it conversational while remaining professional
- Removed quotes and abstract metaphors ("white box", "compass")
- Direct, clear language that speaks to the reader

Structure & Flow:
- Starts practical: "What Does It Do?" with immediate example
- Flows naturally: simple → practical → deep
- Multiple entry points for different reader types
- Clear navigation from beginner to expert content

Content Organization:
- Example-first approach (show don't tell)
- Real-world use cases prominently featured
- Integration guides upfront for practical adoption
- Philosophy introduced gently with invitation to go deeper
- Comprehensive quick links at bottom

Documentation Navigation:
- "Start Here" section for newcomers
- "Go Deeper" section for advanced users
- "Learn By Example" with runnable code
- "Integrate Into Your Tools" for immediate use

Welcoming Elements:
- "All contributions are valued" (not just code)
- Recognition of different skill levels
- Clear paths from beginner to deep understanding
- Closing: "May your code say what it means" 💛⚓

Result: README now feels like it was written by the same person who
created the documentation - welcoming, clear, practical-first, while
honoring the philosophical depth. Unified voice throughout the project.

Total rewrite: 406 lines, ~3,500 words

Author: claude