Add subscription quota rollover guard

[Jorel97]

/claim #20

Summary

• Adds a distinct subscription-quota-rollover-guard/ Revenue Infrastructure slice for issue Revenue Infrastructure #20.
• Audits synthetic subscription AI-compute/token quota ledgers before invoice release for rollover caps, expired lots, duplicate carry-forward, plan downgrade limits, unapproved negative adjustments, overage double-billing risk, and missing finance holds.
• Emits deterministic JSON, Markdown, SVG, GIF, and MP4 demo artifacts from synthetic data.

Non-overlap

This is not another proration, renewal notice, entitlement downgrade, usage replay/idempotency, prepaid credit breakage, committed drawdown, quote approval, invoice delivery, tax, collections, analytics-seat/API, payment authorization, or price-escalation slice. It focuses specifically on unused monthly subscription quota rollover and overage reconciliation before invoice release.

Validation

• npm test -> passed
• npm run demo -> generated reports/quota-rollover-report.json, reports/quota-rollover-report.md, reports/summary.svg, and reports/demo-script.txt
• npm run demo:video -> generated reports/demo.gif and reports/demo.mp4
• git diff --check -> passed

Synthetic data only. No credentials, private customer data, payment processors, Stripe, PayPal, bank/ACH/wallet actions, live billing systems, analytics APIs, or external services are used by this module.

AI-assisted with OpenAI Codex; I reviewed and locally verified the diff before submitting.

[Jorel97]

Clean validation note: added a real MP4 demo artifact at subscription-quota-rollover-guard/reports/demo.mp4 in addition to the existing GIF. Re-ran npm test and npm run demo:video successfully.