[codex] Add pricing experiment guard

[Davifek]

@algora-pbc /claim #20

Summary

Adds a distinct pricing-experiment-guard/ slice for the Revenue Infrastructure bounty. This module helps finance, product, and growth teams decide whether pricing and packaging experiments are safe to launch before customer exposure.

It checks:

• measurable hypothesis and unchanged control cohort readiness
• gross-margin floor compliance for AI-compute-heavy changes
• entitlement regressions without grandfathering
• cohort exposure limits and rollback trigger readiness
• invoice copy, customer notice, tax review, approvals, and revenue-recognition audit evidence

Demo

Included short demo artifact: pricing-experiment-guard/demo.gif

Run locally:

node pricing-experiment-guard/demo.js

Verification

Passed locally:

node pricing-experiment-guard/test.js
node pricing-experiment-guard/demo.js
git diff --cached --check

The tests cover a risky experiment that is blocked, a bounded experiment that is approved, and audit-ready remediation fields for every finding.

Notes

• Dependency-free Node.js standard library implementation
• Synthetic sample data only
• No payment provider, external service, credential, or network access required
• Includes a requirement map for Revenue Infrastructure #20