Add recommendation path auditor

[Davidrsdiaz]

/claim #17

Summary

• add a deterministic recommendation path auditor for the Scientific Knowledge Graph
• detect private node leaks, broken explanation paths, user filter violations, retracted evidence dependencies, weak evidence scores, stale trend features, duplicate recommendations, missing schema metadata, and unexplained personalization
• include synthetic JSON, Markdown, SVG, and short MP4 demo artifacts

Tests

• node scientific-knowledge-graph/recommendation-path-auditor/test.js
• node scientific-knowledge-graph/recommendation-path-auditor/demo.js
• node scientific-knowledge-graph/recommendation-path-auditor/make-demo-video.js

All fixtures are synthetic and the module performs no private graph, account, digest email, credential, ontology-service, or external API access.