Add challenge data-use agreement guard

[yunrongy424-oss]

/claim #18

Adds a standalone Scientific Bounty System slice that validates controlled scientific challenge materials before sponsor review, payout release, or IP handoff.

Data-Use Agreement Guard

• Checks active DUA coverage for controlled and restricted datasets
• Enforces permitted-use alignment before sponsor packets are released
• Holds derived artifacts that expose controlled rows
• Routes export-controlled datasets without clearance to compliance review
• Blocks payout and IP handoff while DUA, retention, or release-scope duties are unresolved
• Redacts team contacts from sponsor-facing packets

Demo And Validation

• Demo video: challenge-data-use-agreement-guard/reports/demo.mp4
• node challenge-data-use-agreement-guard/test.js -> passed
• node --check challenge-data-use-agreement-guard/index.js
• node --check challenge-data-use-agreement-guard/demo.js
• node --check challenge-data-use-agreement-guard/test.js
• node challenge-data-use-agreement-guard/demo.js -> generated JSON/Markdown/SVG reports
• python challenge-data-use-agreement-guard/make-demo-video.py -> generated demo MP4
• MP4 decode/read check returned a 720x1280 RGB frame
• Report spot checks found no synthetic team email/contact leakage
• git diff --cached --check -> clean before commit

Synthetic data only. No private challenge materials, credentials, live DUA systems, identity providers, payment rails, bank data, wallet data, or unrelated source changes are included.