Nexa Mainnet V6 Public Integration

ACTIVE mainnet integration release for Base, BNB Smart Chain and HyperEVM. Includes the verified deterministic Discovery Facade, Registry and Router bindings, signed Feed discovery, ERC-7683 resolver, OIF discovery module, ABI, OpenAPI, network IDs, events, examples, source and identity evidence, and reproducible SHA-256 checksums. Local and GitHub release gates passed validate, tests, production package verification, Worker dry-run and independent onchain verification.