Generate a valid iCalendar (.ics, RFC 5545) file from event data: title, start/end (any ISO 8601 -> UTC), location, description, organizer, attendees. Correct escaping, line-folding and UID. Zero external dependencies, no hallucination. Use it to create calendar invites agents can attach or send. Ed25519-signed. 0.001 USDC on Base. First 3 calls FREE per wallet — send header X-WALLET: 0x<your Base address> (no payment); then per call.