Fix OAuth flow for claude.ai MCP connector (#7)

- Remove initialize from publicMethods so first request gets 401 with
  WWW-Authenticate header, triggering OAuth discovery flow
- Add /oauth/token proxy route to forward token exchange to Keycloak
  (claude.ai uses the discovered token_endpoint URL)
- Switch auth example to use npm package (latest) instead of local ref
- Add request logging for debugging

Author: RahulHere