Add SLA credit revenue guard

[HunterCML]

Summary

/claim #20

Adds a focused SLA credit and revenue adjustment guard for the Revenue Infrastructure bounty. This is a narrow institutional finance-control slice for billing periods where AI compute usage, service outages, and licensing exports must be reconciled before invoice release.

What is included

• tiered plan rules for individual, lab, and institutional subscriptions
• AI compute quota and overage metering
• SLA uptime measurement and capped service-credit calculation
• institutional invoice packet generation with approval/postmortem warnings
• anonymized licensing/API export readiness checks that block private content and weak aggregation
• stable audit digests, requirements map, acceptance notes, static SVG preview, and short H.264 demo video

Validation

• node sla-credit-revenue-guard/test.js
• node sla-credit-revenue-guard/demo.js
• ffprobe confirmed demo.mp4 is H.264 1280x720, 8 seconds

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