Token Permit Signer

EIP-2612 permit lets you authorise a spender with a signature that costs nothing to produce — the spender pays the gas to use it. Probes for nonces() and DOMAIN_SEPARATOR() rather than trusting a token list, reads the EIP-712 version from the contract where it exposes one (a wrong version produces a signature that looks fine and is rejected on chain), and outputs v/r/s plus the full JSON. Warns clearly when a permit is unlimited. Only works on tokens implementing EIP-2612; the app probes for nonces and DOMAIN_SEPARATOR rather than trusting a list. A signature is useless if the spender never submits it, and it stays valid until the deadline passes, so an unlimited permit should be given a short one.