Add 2s.io to Ecosystem

[josho]

Adding 2s.io, a pay-per-call JSON REST API for AI agents.

• 35 endpoints across geo/IP, web extraction & summarization, translation, screenshots, image compression & description, barcodes, DNS/WHOIS, EVM gas oracle, weather, climate, earthquakes/wildfires, Wikipedia, scientific papers, US patents, federal court opinions, Federal Register, OFAC sanctions, US Census demographics, and airport registry.
• Pricing: sub-cent to $0.03 USDC per call on Base mainnet, settled via the Coinbase facilitator.
• No signup required for x402 callers (bearer-account flow in preview).

Discoverable via:

• Service catalog: https://2s.io/api/directory
• OpenAPI 3.1: https://2s.io/openapi.json
• x402 well-known: https://2s.io/.well-known/x402
• llms.txt: https://2s.io/llms.txt

Thanks for maintaining the list!