docs: add example for connecting to existing Chrome via --browserUrl

[liuxiaopai-ai]

Adds a minimal Node example showing how to connect chrome-devtools-mcp to an existing Chrome instance started with --remote-debugging-port=9222.

Why:

• Users frequently run Chrome themselves (custom profiles, corporate policies, Docker, etc.) and just need the MCP server to attach.
• Provides a copy/paste template for stdio transports.

Usage:

• Start Chrome with --remote-debugging-port=9222
• Run node examples/remote-debugging-9222.mjs (or set CHROME_DEBUG_URL)

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[liuxiaopai-ai]

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

[liuxiaopai-ai]

Also updated this example to use the official MCP TypeScript SDK client (Client + StdioClientTransport) instead of direct JSON-RPC.