Add useful error message when docker isn't running

[RachelScodes]

Describe the feature or problem you’d like to solve

The Githup MCP is calling docker to authenticate. If it fails, it doesn't give a reason why.

Proposed solution

Can we wrap the docker call to catch and show a descriptive error? This way the user can self serve: "Could not launch docker. Verify docker is installed and running and try again. See [link to documentation]"

Additional context

I'd be happy to contribute (if you're open to that)