Add gateway capacity cost planning proof

[WaffleBits]

Summary

• add a synthetic capacity/cost planning module tied to configured model policies
• check in aggregate capacity-plan evidence for request, token, latency, utilization, and cost-to-serve review
• document the artifact in the reviewer path, operations notes, architecture, and roadmap

Validation

• python -m unittest discover -s tests
• git diff --cached --check
• public wording scan for target-company, compensation, and desperate-language terms