mcp integration example

This example uses MCP JSON-RPC values in memory and runs the dispatch step in an x.async.Task. It does not start stdio, HTTP, a process transport, or any external service.

The goal is to show the integration boundary:

• build an MCP request value;
• decode and validate it inside a task;
• return an MCP response value;
• consume the result with Task.wait().Run from the repository root:

  ./v run vlib/x/async/examples/mcp/tool_dispatch.v