Cloud session creation can now send the first prompt separately, after permission mode is confirmed
When creating a remote or cloud ("teleport") session, the client can now opt in to a mode where the first prompt is left out of the initial signed session-create request and sent separately afterward, once the permission mode it establishes has been stored on the server. This is controlled by a new deferInitialMessage option, and the create response can indicate the first prompt was withheld so the caller knows to send it itself.
This ensures the permission mode for a new remote session is confirmed and stored before the first prompt is sent, avoiding a case where a prompt could be processed before its governing permission mode is actually in effect.