Add compute meter replay guard

[Gwani-28]

/claim #20

Summary

• Adds a deterministic AI compute metering replay/idempotency guard for Revenue Infrastructure.
• Includes synthetic billing telemetry, JSON and Markdown report outputs, SVG/PNG decision flow artifacts, and a short MP4 demo.
• Flags missing idempotency keys, duplicate replay events, duplicate invoice-line IDs, source sequence gaps, stale corrections, unauthorized negative adjustments, entitlement-plan mismatches, and timestamp-ordering issues.

Validation

• node compute-meter-replay-guard/test/run-tests.mjs
• ffprobe confirmed compute-meter-replay-guard/demo/compute-meter-replay-demo.mp4 is H.264, 1280x720, 8 seconds.

Scope

• Synthetic metering and billing telemetry only.
• No live payment processors, invoices, bank/card data, wallets, customer records, external APIs, tax filing, accounting advice, or legal advice.
• Intended as a pre-invoice reviewer guard before AI compute usage is billed.

Attempt comment: #20 (comment)

AI assistance disclosure: implemented with Codex and manually validated through deterministic tests and generated demo artifacts.