docs: remove unstable user attachment from README

[AetherAI3]

Summary

This branch independently reproduced and repaired the #119 README regression by removing the unproven user-attachment image URL. During qualification, main advanced through the exact same repair in merged PR #121, which added the repository-owned asset and passed the authoritative gates. This PR is therefore a duplicate and must not merge.

FLEET STATUS

• Base SHA: 04ab613aeb677a78b206af4277ef8bb458d1b8ea
• Head SHA: 0fb70279b42d2f22ca331bb971764d2a2e1884a7
• Changed paths: README.md (one deletion)
• Root cause: PR Update README with new image and description #119 left github.com/user-attachments/assets/68c3356d-fe6a-4034-9d18-253a50bb473c in README; public_docs_truth rejects that unstable URL.
• Focused totals: baseline 4/5 (one expected docs-truth failure); repair 5/5.
• Full local totals: 1,853 passed / 4 unrelated Windows Job Object or token-lock failures / 4 skipped / 1,861 total. The failure details were confined to local Windows process-containment and concurrent token-lock stress tests.
• Authoritative exact-head repair evidence on current main (e9cbe448cf4ffef7174620670258a295fb710997, merged PR fix(docs): restore Agent main public-document truth #121): CI run, Ubuntu job, Windows job, supply-chain job, CodeQL run, release-truth run.
• The merged repair is PR #121, using assets/aether-agent-hero.png with packaging and regression validation.
• No runtime, version, or release artifact changed in this branch.
• BLOCKED — duplicate of merged PR fix(docs): restore Agent main public-document truth #121; current main is green. Do not merge.

[AetherAI3]

Closing as a duplicate: PR #121 merged the exact README/public_docs_truth repair and its exact current-main Ubuntu, Windows, supply-chain, CodeQL, and release-truth checks passed.