docs(mcp): add high-level plan for MCP investigation and operations

Introduced a new document detailing the Hookdeck MCP build-out plan v2, focusing on the investigation and operations layer. The plan outlines the goals, scope, and phases of implementation, including success criteria and an end-to-end example of a production investigation workflow. This document serves as a guide for implementers and PMs, ensuring clarity on the MCP's capabilities and limitations.

https://claude.ai/code/session_01Y2eJZgKG78nDyN6Uw2tWQx

Author: leggetter