feat: add client auth request flow

plugin/core/transport.ts

@@ -18,6 +18,8 @@ export interface ClientTransport {
   connect(): Promise<void>;
   disconnect(): void;
   send(message: string): boolean;
+  markAuthenticated(): void;
+  markAuthenticating(): void;
 }
 
 export type ClientMessageHandler = (message: string) => void;