Add artifact replica consistency guard

[haki203]

Summary

• add a self-contained artifact replica consistency guard for Scientific/Engineering Data & Code Hosting
• validate hosted replicas across primary storage, cold archive, institutional mirror, and landing-page metadata before previews, exports, persistent links, or reproduce buttons are enabled
• check checksum agreement, manifest version alignment, access-policy parity, mirror freshness, DataCite DOI consistency, and schema.org landing-page consistency
• emit deterministic repair actions plus JSON, Markdown, SVG, and H.264 MP4 demo artifacts from synthetic data only

Safety

• no storage provider, DOI registry, external mirror, credential, private artifact, external API, or network calls
• synthetic fixtures only in artifact-replica-consistency-guard/sample-data.js

Proof

• artifact-replica-consistency-guard/reports/demo.mp4

Validation

• node --test artifact-replica-consistency-guard/test.js -> 3 tests passed
• node --check artifact-replica-consistency-guard/index.js
• node --check artifact-replica-consistency-guard/test.js
• node --check artifact-replica-consistency-guard/sample-data.js
• node --check artifact-replica-consistency-guard/demo.js
• FFMPEG_PATH=... node artifact-replica-consistency-guard/demo.js -> 3 scenarios, 1 held, 1 repair review, 1 publish
• ffmpeg -v error -i artifact-replica-consistency-guard/reports/demo.mp4 -f null NUL
• git diff --check
• git diff --cached --check

/claim #14

[haki203]

@algora-pbc /claim #14 #373