Add notebook result replay ledger

[FeeeeelixWong]

/claim #10

Summary

Adds a focused notebook/result replay ledger for the Project Repository & Version Control bounty. This is intentionally narrower than another broad repository ledger: it validates whether result artifacts were produced from the current notebook, data, code, and environment hashes before a release candidate is cited or published.

What is included

• Dependency-free replay ledger core in notebook-result-replay-ledger/src/replay-ledger.js
• Scientific sample repository manifest with data/code/notebook/environment/result evidence
• Release gating for stale or failed replay outputs
• Rollback packets and citation badge impact notes
• Node test coverage and local CLI demo
• Requirement map for Project Repository & Version Control #10
• Short demo video: notebook-result-replay-ledger/docs/demo.mp4

Demo

The demo video shows a release candidate blocked because one figure was generated from older data/code/notebook/environment hashes and one QC result failed replay after the environment changed. A clean model metrics artifact remains publishable.

Verification

cd notebook-result-replay-ledger
npm run check
npm test
npm run demo
ffprobe -v error -select_streams v:0 -show_entries stream=codec_name,width,height,duration -of default=noprint_wrappers=1 docs/demo.mp4

I also ran:

git diff --check -- notebook-result-replay-ledger
rg -n "api[_-]?key|private[_-]?key|password|secret|token|wallet|ssn" notebook-result-replay-ledger