Add payment dispute evidence guard

[daxia778]

Summary

• Add a self-contained payment-dispute-evidence-guard module for the Revenue Infrastructure bounty in Revenue Infrastructure #20.
• Evaluate synthetic processor dispute packets for response deadlines, required evidence, prior refund or credit offsets, duplicate processor case IDs, customer notice timing, receipt redaction, and revenue-at-risk handling.
• Generate reviewer artifacts as JSON, Markdown, SVG, and WebM without payment processor calls, credentials, bank data, real customer records, or external APIs.

/claim #20

Validation

• npm test -> 4 tests passed
• npm run demo -> generated JSON, Markdown, and SVG reviewer artifacts
• npm run demo:video -> generated payment-dispute-evidence-guard/artifacts/dispute-review-demo.webm
• WebM artifact check -> dispute-review-demo.webm exists, 37,688 bytes, EBML signature 1a45dfa3
• git diff --check

Generated demo artifacts:

• payment-dispute-evidence-guard/artifacts/dispute-review-report.json
• payment-dispute-evidence-guard/artifacts/dispute-review-report.md
• payment-dispute-evidence-guard/artifacts/dispute-review-demo.svg
• payment-dispute-evidence-guard/artifacts/dispute-review-demo.webm

[daxia778]

@algora-pbc /claim #20\n\nAdded the requested short demo video artifact in commit 76942a4:\n\n- npm run demo:video now generates payment-dispute-evidence-guard/artifacts/dispute-review-demo.webm\n- committed WebM artifact is 37,688 bytes with EBML signature 1a45dfa3\n- validation re-run: npm test, npm run demo, npm run demo:video, and git diff --check