docs: establish the credentialed Claim Economy

[BrandonDucar]

Summary

• model Claim Factories as staffed organizations with University credentials
• require independent verifier factories and deterministic promotion
• define Claim Cities and cross-domain federation boundaries
• document Cerberus orange escalation alongside green/yellow/red
• link the public claim-factory reference implementation

Verification

• npm run verify
• Cerberus GREEN 0/100 for commit 635b26c
• content digest sha256:8e49b1d60aa14205fee5bea9409cedc56c17340376e074ad4af475d617b700ad