[Luca Forstner (lforst)]

• Add automatic tracing for Model Context Protocol (MCP) v1 and v2 servers, capturing tool calls, prompt retrievals, and resource reads.
• Add wrapMCPServer() for manually enabling tracing on an existing server:

  import { wrapMCPServer } from "braintrust";
  
  wrapMCPServer(server); // Trace existing and future request handlers.

• Record inputs, outputs, and session/request IDs so related requests can be correlated. Mark tool results with isError: true as failures even when the handler doesn't throw.
• Omit response _meta and inline media bytes from traces. Capture images and resource blobs as attachments when enabled; always omit audio and video bytes.