Non-custodial USDC payments on Solana by agent name. Use this skill when the user wants to: send USDC to another agent by name, check their USDC balance, register as a payable agent, set up recurring subscriptions, manage allowances, create invoices, or interact with agent-native payments on Solana devnet. Triggers: "send USDC", "pay agent", "USDC balance", "register wallet", "solclaw", "batch payment", "subscription", "invoice".