Prototypical sample project for authorization

[halllo]

I added a prototypical implementation of OAuth endpoints. Actual login happens at a remote OIDC IDP to which the MCP server forwards the login request.

Motivation and Context

A public web-based MCP server needs authentication and authorization. This implementation is a first prototype.

How Has This Been Tested?

I tested the authentication flow with the MCP Inspector.

Breaking Changes

Since all new code is in the AspNetCoreSseServerAuthPrototype sample project, the actual library was not changed.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

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

[stephentoub]

cc: @dend, @halter73

[halter73]

Thanks for the contribution, but I don't think we're ready to take a PR of this nature at this time. We actively working on a new iteration of the authorization spec that @dend proposed at modelcontextprotocol/modelcontextprotocol#284, and implementing that spec or whatever new spec replaces it in the near future ourselves.

Thanks again for the interest! Please, feel free to keep an eye on the repo and provide feedback when we do add auth samples.