Add artifact package integrity gate

[HunterCML]

Summary

/claim #14

Adds a self-contained artifact-package-integrity-gate module for Scientific/Engineering Data & Code Hosting. The module validates reviewer-ready research artifact packages before they are exposed through persistent links, DOI metadata, export packets, or reproducible rerun buttons.

Covered scope:

• classifies datasets, notebooks, code, figures, media, and model artifacts
• builds metadata-aware preview plans and persistent artifact links
• validates DataCite, JSON-LD, schema.org, artifact metadata, licenses, restricted access evidence, and version hashes
• verifies pinned executable environments and rerun command inputs
• emits deterministic source/package digests for reviewer packets and archive/API workflows

Evidence

• artifact-package-integrity-gate/demo.mp4 short H.264 demo video
• artifact-package-integrity-gate/demo.svg static reviewer dashboard preview
• artifact-package-integrity-gate/requirements-map.md
• artifact-package-integrity-gate/acceptance-notes.md

Validation

• node artifact-package-integrity-gate/test.js
• node artifact-package-integrity-gate/demo.js
• git diff --check
• ffprobe -v error -select_streams v:0 -show_entries stream=codec_name,width,height,duration,pix_fmt -of default=noprint_wrappers=1 artifact-package-integrity-gate/demo.mp4