Add Git LFS pointer integrity guard

[attaboy11]

/claim #10

Summary

• Adds a self-contained lfs-pointer-integrity-guard/ module for the Project Repository & Version Control bounty.
• Audits Git LFS pointer syntax, object SHA-256 and byte-size parity, missing large-object storage entries, release/export manifest coverage, DOI bundle inclusion, retention windows, and quota risk before tagged releases or export bundles proceed.
• Generates deterministic JSON, Markdown, SVG, and MP4 reviewer artifacts using only synthetic data and no external services.

Scope distinction

This is focused specifically on Git LFS-backed large scientific files and hash-based integrity. It is separate from existing broad repository ledgers, component-owner approval, semantic version tagging, external reference pinning, notebook output diffing, fork provenance, release signature, restore rehearsal, compute sandbox, retention/legal-hold, embargo-release, branch-protection drift, and artifact-prune slices.

Validation

• node lfs-pointer-integrity-guard/test.js
• node lfs-pointer-integrity-guard/demo.js
• node lfs-pointer-integrity-guard/render-video.js
• node --check lfs-pointer-integrity-guard/index.js
• node --check lfs-pointer-integrity-guard/sample-data.js
• node --check lfs-pointer-integrity-guard/test.js
• node --check lfs-pointer-integrity-guard/demo.js
• node --check lfs-pointer-integrity-guard/render-video.js
• git diff --check
• ffprobe -v error -select_streams v:0 -show_entries stream=pix_fmt,width,height -show_entries format=duration,size -of default=nw=1 lfs-pointer-integrity-guard/reports/demo.mp4

MP4 check result: width=960, height=540, pix_fmt=yuv420p, duration=4.000000, size=25899.