feat: add authlete to provider lists

[watahani]

Summary

This PR adds Authlete to the documented list of identity providers tested with MCP Auth.

What’s included:

• Updates to the Provider list page to include Authlete, with ✅ for all supported features.
• Adds a new column for "Client ID Metadata Document" to the provider list table.
• Updates the documentation to clarify that Client ID Metadata Document is now the primary method for dynamic registration, with Dynamic Client Registration mentioned for backward compatibility.

Test plan

<TestProvider /> does not check client_id_metadata_document_supported, but for CIMD we have tested it using a combination of VS Code, mcp-auth, and the authorization server using Authlete and confirmed that it works correctly.

[watahani]

@xiaoyijun Could you please review this PR? I’ve added tables related to CIMD and replaced some explanations; if they’re unnecessary, I can remove them, so please let me know.