docs: refocus README on self-learning browser

[askadityapandey]

Summary

• refocus the README on live browser control and self-learning memory
• remove public adapter and plugin messaging from positioning, setup, examples, and links
• add a branded self-learning flow diagram
• refresh the hero's right-side mockup while preserving the approved copy

Testing

• git diff --check
• verified all README image references resolve on the branch
• verified the required one-skill public-copy language remains present

Screenshots / Output

The updated hero and self-learning diagram are included directly in the README.

[github-actions]

🟠 Maintainer review suggested — low confidence

The automated review could not reach a fully supported conclusion.

This review is advisory and does not block merging.