Add sample chain-of-custody review assistant

[Gwani-28]

/claim #16

Summary

• Adds a deterministic sample chain-of-custody review assistant for AI research release checks.
• Includes a synthetic custody packet, JSON and Markdown report outputs, SVG/PNG decision flow artifacts, and a short MP4 demo.
• Flags missing consent links, missing signed handoffs, time gaps, temperature excursions, blinding leaks, failed assay QC, open quarantine, missing reviewer signoff, and conclusion release gates.

Validation

• node sample-chain-of-custody-assistant/test/run-tests.mjs
• ffprobe confirmed sample-chain-of-custody-assistant/demo/sample-chain-of-custody-demo.mp4 is H.264, 1280x720, 8 seconds.

Scope

• Synthetic sample metadata only.
• No external APIs, credentials, private records, medical advice, or regulatory/legal advice.
• Intended as a reviewer guardrail before AI-generated research conclusions are released.

Attempt comment: #16 (comment)

AI assistance disclosure: implemented with Codex and manually validated through deterministic tests and generated demo artifacts.