196b9598e6
`MCPServer(token_verifier=...)` no longer needs `auth=AuthSettings(...)`. On its own a verifier is now a plain bearer gate: requests without a token it accepts get a 401 whose `WWW-Authenticate` carries no `resource_metadata`, no protected-resource metadata route is published, and `get_access_token()` works as before. `AuthSettings` keeps its job of describing that gate to OAuth clients (required scopes, RFC 9728 metadata, the discovery pointer in the 401), so it is what you add when a real authorization server issues the tokens. Previously the constructor refused a verifier without settings, which forced anyone with a pre-shared token to invent an issuer URL, and the low-level `Server.streamable_http_app(token_verifier=...)` accepted the same shape but answered every request 401, valid token included, because the authentication backend was only installed when settings were given. Both wiring sites (and `MCPServer.sse_app`) now install the backend whenever a verifier is present. The authorization docs gain a "Just a pre-shared token" section with a runnable example, and the constructor still refuses the two shapes that cannot work: settings with nothing to gate with, and an embedded authorization-server provider without settings for its issuer.