Open the standalone server->client stream (HTTP GET SSE), so the server
can deliver sampling / elicitation / roots requests and notifications
outside of any request response. A no-op on stdio (and tolerated as a
no-op when an HTTP server does not offer the stream).
Open the standalone server->client stream (HTTP GET SSE), so the server can deliver sampling / elicitation / roots requests and notifications outside of any request response. A no-op on stdio (and tolerated as a no-op when an HTTP server does not offer the stream).