ecosystem: add TK Base x402 APIs (Polymarket Scan, Polymarket Liquidity, Token Intelligence)

[TKtokyo]

Summary

Adds three x402-powered APIs on Base mainnet to the x402 ecosystem page.

1. Polymarket Scan API

• Endpoint: https://polymarket-scan-api.tatsu77.workers.dev
• Automated Polymarket market scanner detecting liquidity anomalies and trade opportunities
• Scans all active markets every 60s via Cron
• $0.018 USDC per scan, $0.005 USDC for 24h history

2. Polymarket Liquidity API

• Endpoint: https://polymarket-liquidity-api.tatsu77.workers.dev
• Real-time order book depth, spread analysis, and market efficiency scoring
• $0.005 USDC per request

3. Token Intelligence API

• Endpoint: https://token-intel-api.tatsu77.workers.dev
• EVM token security analysis with deterministic risk scoring
• $0.005 USDC per request

Verification

• Listed on xpay✦ Tools (3 services, all active)
• Listed on awesome-x402 (PR feat: added correlation-context header to cdp facilitator requests #125 merged)
• /.well-known/x402 discovery endpoint live on all 3 APIs
• llms.txt live on all 3 APIs
• Base mainnet, USDC, no API key required