Replace the inherited Grim README with one that reflects what Goblin actually
is: a private, Cash App-style GRIN wallet that pays @usernames via NIP-17
gift-wrapped DMs over Tor, with in-app nostr identity and the goblin.st
identity service. Adds the Goblin banner, a payment-flow diagram, correct
build instructions (binary is `goblin`), and keeps the Claude credit.
Claude
