Structural tag MCP-style tool calls

Run npm install, then npm start to launch a minimal page that prints progress and logs to the browser console.

This example demonstrates how to:

• Define a structural tag that forces an MCP-style <tool_call>...</tool_call> block with {"name": ..., "arguments": ...} payloads.
• Ask WebLLM for a tool call with response_format.type = "structural_tag", parse the call, and dispatch to a stubbed tool implementation.
• Send the tool result back via a tool message and request a final natural-language answer.

Open the console to see the enforced tool call, the stubbed tool response, and the final assistant reply.