docs: awesome-ready README with hero + doc-view screenshots (#20)

- Add centered header with tagline, quick links, and badges
  (live, MIT, npm CLI, Next.js, PRs welcome)
- Add hero + rendered-doc screenshots (hosted on PixelVault CDN)
- Sharpen agent-native positioning
- Add "What it looks like" preview section

Prep for submission to awesome-selfhosted / awesome-ai-agents.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>