Checks (conditional escrow)

Say it in the chat: “write a check for $5 to alice for the logo”. A check is a programmable, escrow-backed payment: you write one to a GROX user or a wallet address and the amount is held up front. The recipient cashes it when ready; you can void it (full refund) any time before it’s cashed; and it auto-refunds if it expires. Cashing issues a verifiable receipt. “Cash the check from bob” and “void my check to alice” work in chat too.