chore: initialize sandbox and overwrite remote content

examples/agent/a2ui_agent/samples/client/lit/contact/README.md

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+# A2UI Generator
+
+This is a UI to generate and visualize A2UI responses.
+
+## Prerequisites
+
+1. [nodejs](https://nodejs.org/en)
+
+## Running
+
+This sample depends on the Lit renderer. Before running this sample, you need to build the renderer.
+
+1. **Build the renderer:**
+   ```bash
+   cd ../../../renderers/lit
+   npm install
+   npm run build
+   ```
+
+2. **Run this sample:**
+   ```bash
+   cd - # back to the sample directory
+   npm install
+   ```
+
+3. **Run the servers:**
+   - Run the [A2A server](../../../agent/adk/contact_lookup/)
+   - Run the dev server: `npm run dev`
+
+After starting the dev server, you can open http://localhost:5173/ to view the sample.