ERC-1920 Standardizes Claims With Weighted Verification Gates

ERC-1920 standardizes claim verification with four transitions — offer, verify, settle, revoke. Fixed state machine: Offered → Verified → Settled; Revoked reachable from live states. No self-verification; weight, not count, drives promotion. Out of scope: payments, identity, weights. Built from two production systems; Foundry reference implementation exists. Draft in ethereum/ERCs PR #1920.