Add pointing UIWorker example

The voice LLM delegates to a ReplyToolMixin UIWorker that scrolls offscreen
items into view and highlights the phones it names — exercising the scroll_to /
highlight UI commands and the [offscreen] state tag.

examples/multi-worker/ui-worker/pointing/client/vite.config.js

@@ -0,0 +1,7 @@
+import { defineConfig } from "vite";
+
+export default defineConfig({
+  server: {
+    port: 5173,
+  },
+});