feat: add native module realtime transport

packages/module-ui-sdk/src/host-context.ts

@@ -1,3 +1,5 @@
+import type { ModuleUiRealtimeClient } from "./realtime.js";
+
 /**
  * Who is viewing, as a browser sees it.
  *
@@ -53,6 +55,8 @@ export interface ModuleUiHostContext {
   readonly principal: ModuleUiPrincipal;
   /** Presentation-only permission hints. See {@link ModuleUiPermissions}. */
   readonly permissions: ModuleUiPermissions;
+  /** Host-owned delivery of this module's own runtime-published state. */
+  readonly realtime: ModuleUiRealtimeClient;
 }
 
 /**