docs: add minimal Node client example

[liuxiaopai-ai]

Adds a tiny, dependency-free Node example that spawns the server via npx and sends an MCP initialize request.

Why:

• Provides a copy/paste smoke check for users debugging stdio transports.
• Keeps the example small and avoids introducing new build/test requirements.

Notes:

• Example is intentionally minimal and exits after receiving the initialize response.

[google-cla]

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[liuxiaopai-ai]

CLA has now been signed with this GitHub account. Could you please re-run/check the cla/google status? Thanks!

[OrKoN]

Thanks for the PR but I think we should not document direct interactions with MCP and instead rely on the MCP SDK client implementations documented here https://modelcontextprotocol.io/docs/develop/build-client#typescript

[liuxiaopai-ai]

Thanks for the feedback — updated. I replaced the direct JSON-RPC interaction example with an official MCP TypeScript SDK client example (Client + StdioClientTransport) and updated the README wording accordingly.