Add credit role evidence consistency guard

[cwklurks]

Summary

• Adds a distinct CRediT role evidence consistency guard for issue Community & User Reputation System #15.
• Validates contributor credit claims before they affect profiles, citation pages, leaderboards, or institutional exports.
• Checks role taxonomy support, consent, missing evidence, role/evidence mismatch, blind-review identity leaks, author self-review conflicts, duplicate credit claims, and stale evidence.
• Uses synthetic data only and generates JSON, Markdown, SVG, and MP4 reviewer artifacts.

/claim #15

Proof

• Demo artifacts are in credit-role-evidence-guard/reports/.
• Short demo video: credit-role-evidence-guard/reports/demo.mp4.
• Reviewer packet: credit-role-evidence-guard/reports/reviewer-packet.json.
• Human-readable report: credit-role-evidence-guard/reports/reviewer-report.md.

Validation

• npm run check
• npm test
• npm run demo
• ffprobe -v error -show_entries format=duration,size -show_entries stream=codec_name,width,height -of default=noprint_wrappers=1 credit-role-evidence-guard/reports/demo.mp4
• git diff --check

Safety

• Synthetic fixtures only.
• No credentials, private user data, external APIs, live profiles, payment details, or network calls are used by the module.
• AI-assisted with OpenAI Codex; I reviewed and locally verified the diff before submitting.