Add NuGet to the MCP Registry, similar to npm and Python

[joelverhagen]

Motivation and Context

This resolves #126.

As of .NET 10 Preview 6 (releasing on July 8th, 2025), .NET has a single-shot command similar to npx and uvx. It is called dnx.

This allows .NET tool packages hosted on NuGet.org to be executed much like npm or PyPI packages.

I have added NuGet to a lot of the places Python and npm exist today. If it is too many places, I am happy to trim it down!

How Has This Been Tested?

I a sample MCP server hosted on nuget.org and running in my VS Code using dnx.

Breaking Changes

None.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
  • Add nuget as a supported registry_name
  • Add dnx as an example runtime_hint
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
  • Add a guide on how to add a new package registry

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

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