robot-md v1.4.0: plug a servo bus and Claude announces it

v1.4.0 ships three independent feature tracks that, together, change what registering a new piece of hardware feels like: hot-plug detection at the OS level, an announce/confirm UX over MCP that lets Claude talk the operator through the bind, and the first half of SP6's self-attestation loop — robots now sign their own spatial-intelligence scores with their RCAN apikey.