Persist Codex 0.140 checkpoint decisions

[yvette-carlisle]

Summary

• refresh openai/codex release_delta/v1 to latest prerelease rust-v0.140.0-alpha.21
• add terminal social_candidate/v1 defer records for rust-v0.140.0-alpha.20 and rust-v0.140.0-alpha.21
• record exact adjacent compare windows, PR-title gap lists, and source-analysis next steps

Decision

• alpha.20: decision.worthiness = defer, reason = needs_upstream_analysis after partial reviewed coverage plus unreviewed PR-title gaps
• alpha.21: decision.worthiness = defer, reason = needs_upstream_analysis because all named adjacent-window PRs lack checked review/impact evidence

Validation

• jq -e on the new social candidates and refreshed release-delta JSON
• cargo run -p decodex --bin decodex -- radar validate artifacts/github/social-candidates site/src/content/release-deltas
• git diff --cached --check

Notes

• This PR does not publish to X.
• No generated media is attached.
• Official Codex changelog still tops out at Codex app 26.609 on 2026-06-11 for this run.