Add x402 payment example with Bug Bounty Intelligence — MCP + x402 combined

Following #167 (Intelica) — another concrete x402-paid MCP example, this one for smart contract security.

Bug Bounty Intelligence ships as both an MCP server (bug-bounty-intelligence-mcp on npm) and a standalone x402 HTTP endpoint, so it might be a useful second reference for anyone building on mcp-handler who wants to see the MCP-plus-payment combination end to end rather than just the payment side.

• Endpoint: https://wazir-x402.duckdns.org/api/bug-intel (5 USDC, Base)
• MCP package: bug-bounty-intelligence-mcp on npm

Happy to trim this down to whatever format the other example uses.