[Renderer] React Native Implementation

## Summary

I'm building a React Native renderer for A2UI, following the [Renderer Implementation Guide](https://a2ui.org/guides/renderer-development/).

React Native support is listed on the roadmap but doesn't have an implementation yet. This renderer will enable A2UI-compliant agents to generate native mobile UIs on iOS and Android.

## Repository

https://github.com/sivamrudram-eng/a2ui-react-native

## Current Status (MVP)

### Implemented Features

- **JSONL Stream Parser** - Real-time parsing of A2UI streaming responses
- **Message Dispatcher** - Routes `beginRendering`, `surfaceUpdate`, `dataModelUpdate`, `deleteSurface` messages
- **Surface Registry** - Manages multiple rendering surfaces with component buffers
- **Data Binding** - Full `BoundValue` resolution (literal and path-based)
- **Main Renderer Component** - `A2UIRenderer` that renders the component tree

### MVP Components (8 of 16)

| Component | Status | React Native Mapping |
|-----------|--------|---------------------|
| Text | ✅ | `` |
| Button | ✅ | `` |
| Image | ✅ | `` |
| Row | ✅ | `` |
| Column | ✅ | `` |
| Card | ✅ | `` with shadow |
| List | ✅ | `` |
| TextField | ✅ | `` |

### Planned Components

- Modal, Tabs, Slider
- DateTimeInput, Checkbox, MultipleChoice
- Video, AudioPlayer, Icon, Divider

## Usage Example

```tsx
import { A2UIRenderer } from 'a2ui-react-native';

const App = () => {
const spec = {
surfaceId: 'main',
rootId: 'root',
components: [
{ id: 'root', type: 'Column', children: ['text1', 'btn1'] },
{ id: 'text1', type: 'Text', content: 'Hello A2UI!' },
{ id: 'btn1', type: 'Button', label: 'Click me', action: 'doSomething' },
],
};

return ;
};

Roadmap

- Complete MVP testing with example app
- Add remaining standard components
- Publish to npm
- Add streaming hook (useA2UIStream)
- Submit PR to add to official renderers list

Questions for Maintainers

1. Are there any specific requirements for official renderer inclusion?
2. Should I follow the same directory structure as the Lit/Angular renderers?
3. Any feedback on the implementation approach?

I'd welcome any feedback or guidance. Happy to collaborate with the team on this!

---

Would you like me to help you with anything else after posting the issue, such as:
1. Installing dependencies and testing the build
2. Creating an example Expo app
3. Adding the streaming hook (`useA2UIStream`)

The issue describes a substantial new renderer implementation. Start by reviewing the existing repository at https://github.com/sivamrudram-eng/a2ui-react-native to see the current MVP status and component mappings. Examine the Renderer Implementation Guide linked in the issue for architectural requirements. The work involves completing the remaining planned components, testing, and preparing for an official PR.

Rédigé par le modèle d'indexation à partir du texte de l'issue.