Add portfolio proof snapshot to the README

[gabedalmolin]

Summary

Strengthen the repository's portfolio proof surface by adding a versioned visual snapshot and aligning the README release link with the current release flow.

Advances #41

What changed

• add a versioned SVG proof snapshot that summarises security, observability, benchmark, and delivery signals
• surface the proof snapshot near the top of the README for faster reviewer scanning
• update the release badge link to use the latest release endpoint instead of a fixed v1.0.0 URL
• link the proof snapshot from the operational proof section so the asset stays discoverable

Validation

• npm run lint
• npm run typecheck

Risks/Notes

• this PR advances the portfolio narrative, but issue Polish portfolio proof assets and repository narrative #41 still depends on the public demo from Ship a public demo environment for the auth API #40 and the final v1.1.0 release