[codex] Add FAIR artifact access gate

/claim #14

Addresses #14

Summary

adds a dependency-free FAIR artifact access gate for scientific data and code hosting readiness
catalogs mixed scientific artifact families with persistent URLs, access policies, preview support, versioning, and deterministic hashes
checks JSON-LD, DataCite, schema.org, FAIR signals, restricted reviewer access, and deterministic reviewer export packets
includes demo assets at fair-artifact-access-gate/docs/demo.svg and fair-artifact-access-gate/docs/demo.mp4

Fresh validation on 2026-05-17 21:18 PDT from a /tmp checkout of this PR:

npm test -> completed successfully with exit code 0
npm run demo -> project Astrocyte Calcium Imaging Atlas, ready yes, FAIR findable/accessibile/interoperable/reusable all pass, 10 reviewer packet entries, packet hash 41a0bf60268a3bdbd1761ed7d68d8a8f324750ad8accb6c2b57374463d909d16, blockers none
npm run demo:video -> renderer completed and wrote docs/demo.mp4
file docs/demo.mp4 docs/demo.svg -> MP4 v2 and SVG image data
git diff --check -> clean
rg -n "(api[_-]?key|secret|token|password|private[_-]?key|wallet|0x[a-fA-F0-9]{40})" fair-artifact-access-gate -> no matches