[codex] Add knowledge graph retraction guard

[newmattock]

/claim #17

Summary

• add a self-contained knowledge-graph retraction guard
• propagate retraction, correction, and expression-of-concern notices through graph entities and evidence relationships
• emit severity-ranked findings, recommendation decisions, curator actions, JSON-LD evidence, deterministic audit digests, and demo artifacts
• include synthetic graph data, requirement mapping, SVG/GIF demo artifacts, a short MP4 demo video, CLI demo, and Node tests

Distinctness

This slice focuses on graph integrity after publication notices alter the trustworthiness of cited evidence. It avoids duplicating broad graph builders, search/recommendation engines, ontology importers, evidence scoring, citation extraction, curation queues, and provenance dashboards already submitted by others.

Demo

• knowledge-graph-retraction-guard/docs/demo.mp4
• knowledge-graph-retraction-guard/docs/demo.gif
• knowledge-graph-retraction-guard/docs/demo.svg
• cd knowledge-graph-retraction-guard && npm run demo

Validation

• npm run check
• npm test
• npm run demo
• git diff --check
• verified docs/demo.mp4 is ISO Media MP4
• verified docs/demo.gif renders as 960x540 with 3 frames

AI-assisted with OpenAI Codex; I reviewed and locally verified the diff before submitting.