Persist upstream Radar review artifacts

[yvette-carlisle]

Summary

• refresh the openai/codex upstream review queue
• add source-backed review, impact, bundle, and social-candidate artifacts for PRs 26687, 26486, 26934, and 26840
• keep the source-analysis automation boundary: no social_post/v1 records and no X publishing

Validation

• cargo run -p decodex --bin decodex -- radar bundle validate artifacts/github/bundles/openai-codex-pr-26687.json artifacts/github/bundles/openai-codex-pr-26486.json artifacts/github/bundles/openai-codex-pr-26934.json artifacts/github/bundles/openai-codex-pr-26840.json
• cargo run -p decodex --bin decodex -- radar validate artifacts/github/review-queue artifacts/github/bundles artifacts/github/reviews artifacts/github/impact artifacts/github/social-candidates
• cargo make check-site-content
• cargo make fmt
• cargo make lint-fix
• cargo make test