[Bug]: AGUI Middleware is missing for MCP apps with google adk framework not redenring ui tool like langraph with mcp middleware

### Pre-flight Checklist

- [x] I have searched [existing issues](https://github.com/ag-ui-protocol/ag-ui/issues) and this hasn't been reported yet.
- [x] I am using the **latest** version AG-UI.

### Describe the Bug

when we are using mcp middleware for langgraph agent the mcp app tool is directly rendering the ui component as in frame in the chat window. However when we are working with google adk framework it is not rendering to render it we need to additionality define the render tool after that it will render the ui mcp app with copilotkit

common configuraiton with middleware

import { MCPAppsMiddleware } from '@ag-ui/mcp-apps-middleware';
import { HttpAgent } from '@ag-ui/client';

const agent = new HttpAgent({
url: `http://127.0.0.1:8094`, // single POST endpoint
});

agent.use(
new MCPAppsMiddleware({
mcpServers: [
{
type: 'http',
url: mcpUrl,
serverId: 'spider-mcp',
},
],
}),
);

### Steps to Reproduce

create mcp apps
intergrate with agent and copilotkit
mcpmiddleware for mcp tool and test with google adk agent

### Expected Behavior

UI tools should automatically render same like langgraph agent

### Environment

```text
Node 22/ Python 3.13
```

### Screenshots

_No response_

### Logs & Errors

```shell

```

### Additional Context

_No response_