Add client runtime and hello handshake

plugin/index.ts

@@ -24,6 +24,13 @@ export {
   type ClientStateChangeHandler,
   type ClientErrorHandler
 } from "./core/transport.js";
+export {
+  createYonexusClientRuntime,
+  YonexusClientRuntime,
+  type YonexusClientRuntimeOptions,
+  type YonexusClientRuntimeState,
+  type YonexusClientPhase
+} from "./core/runtime.js";
 
 export interface YonexusClientPluginManifest {
   readonly name: "Yonexus.Client";