Add storage overage billing guard

[xiejesses]

@algora-pbc /claim #20

Reviewer Path

• Start with storage-overage-billing-guard/requirements-map.md for issue coverage and scope boundaries.
• Inspect storage-overage-billing-guard/index.js and storage-overage-billing-guard/test.js for quota, charge, hold, and retention-conflict logic.
• Use storage-overage-billing-guard/reports/storage-overage-report.md, storage-overage-billing-guard/reports/summary.svg, and storage-overage-billing-guard/reports/demo.mp4 for the finance-review demo.

Summary

• Add a self-contained storage overage billing guard for Revenue Infrastructure.
• Reconcile private project storage, dataset snapshots, reproducibility artifacts, and licensed-export caches against plan quotas.
• Flag unmetered external buckets, stale retention candidates, and deletion requests blocked by legal hold.
• Emit deterministic JSON, Markdown, SVG, and H.264 MP4 reviewer artifacts from synthetic data.

Sponsor Outcome

The sponsor gets a narrow revenue-control slice for a concrete leakage path: storage usage is reconciled before invoice release. Clean overage becomes invoice-ready, questionable storage is held for ops review with explicit reasons, and protected data is separated from purge candidates.

Scope Boundaries

This is not another generic billing ledger, seat or renewal true-up, metering ledger, payment webhook validator, payment failover module, dispute guard, SLA credit calculator, royalty settlement, revenue forecast, FX reconciliation, procurement control, invoice acceptance gate, sanctions/export-control gate, consortium pricing gate, trial/promotion abuse guard, plan-proration module, or AI compute idempotency meter.

This slice focuses specifically on storage quota reconciliation and retention evidence before storage-related revenue reaches the invoice.

Validation

• cd storage-overage-billing-guard && npm run check
• cd storage-overage-billing-guard && npm test
• cd storage-overage-billing-guard && npm run demo
• ffprobe -v error -show_entries format=duration,size -show_entries stream=codec_name,width,height -of default=noprint_wrappers=1 storage-overage-billing-guard/reports/demo.mp4
• git diff --check

Demo Artifacts

• storage-overage-billing-guard/reports/demo.mp4 - H.264, 960x540, 6 seconds
• storage-overage-billing-guard/reports/summary.svg
• storage-overage-billing-guard/reports/storage-overage-packet.json
• storage-overage-billing-guard/reports/storage-overage-report.md

AI-assisted with OpenAI Codex; reviewed and locally verified before submission.