ERC-20 token metadata — name, symbol, decimals, total supply — for any token contract on Ethereum, Base, Arbitrum, Optimism, Polygon, or BNB Chain. Optionally include a "holder" address to also read that wallet's balance. Public JSON-RPC reads, no API keys. POST a JSON body like: {"chain":"base","address":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"}