Support authentication

[Nek-12]

Using SSE servers with auth is not possible right now. We have to support auth somehow, but how? The MCP spec forbids usage of auth with stdio servers (which we are).

My current solution is to create an --auth command to authenticate the MCP itself, and the MCP will duplicate auth functionality of the agent e.g. CC.

But I don't want this MCP be involved in security. Vibe coding auth in an MCP is a suicide pact ☠️.

For now I don't see any better alternatives than to implement a full blown auth system.