Clean up README presentation - #50

Summary

• consolidate the README hero into one centered HTML container
• make the version, PyPI, and license badges clickable and add meaningful alt text
• add descriptive alt text to the architecture figure
• remove the redundant two-item table of contents

Why

The previous hero used several fragmented and empty containers, decorative badges lacked accessible labels or destinations, and the short manual table of contents duplicated GitHub's built-in outline.

Impact

The README source is simpler, the hero remains visually equivalent, and screen-reader users receive useful descriptions for badges and the architecture diagram.

Validation

• git diff --check
• rendered the complete README with GitHub's Markdown API
• verified the consolidated hero and architecture image alt text in rendered HTML
• confirmed the Table of Contents heading is absent