Add sample custody quality graph guard

[AlonePenguin]

Summary

• Adds a self-contained sample custody and cold-chain quality graph guard for issue Scientific Knowledge Graph Integration #17.
• Validates collection provenance, preservation timing, signed custody handoffs, cold-chain temperature logs, freeze-thaw limits, integrity scores, required sample graph edges, and recommendation-safe hold/remediation actions before sample nodes publish.
• Includes synthetic clean/risky packets plus JSON, Markdown, SVG, and MP4 reviewer artifacts.

Non-overlap

This is a sample custody/cold-chain quality slice, separate from existing broad graph extraction/navigation, geospatial sample provenance, organism/strain boundaries, biological accession crosswalks, measurement harmonization, software dependency provenance, evidence freshness, temporal validity, image metadata provenance, funding provenance, and clinical-trial registry submissions.

Verification

• npm run check
• npm test
• npm run demo
• npm run verify-video
• git diff --check
• git diff --cached --check

/claim #17