feat: add React renderer and sample clients

- Add @a2ui/react renderer with ShadCN-inspired Tailwind components
- Implement core A2UI components: Text, Button, Card, Row, Column, List, etc.
- Add A2UIProvider and ThemeProvider context providers
- Add useA2UI and useDataBinding hooks for state management
- Include 64 unit tests with full coverage
- Add React sample clients: contact, restaurant, gallery, rizzcharts, orchestrator
- Add a2a-chat-canvas component for chat interfaces

Author: abalmush

renderers/react/README.md

@@ -0,0 +1,249 @@
+# @a2ui/react
+
+A React renderer for the A2UI protocol with ShadCN-style components and Tailwind CSS.
+
+## Installation
+
+```bash
+npm install @a2ui/react
+```
+
+### Peer Dependencies
+
+This package requires the following peer dependencies:
+
+```bash
+npm install react react-dom tailwindcss
+```
+
+## Quick Start
+
+### 1. Set up Tailwind CSS
+
+Ensure your project has Tailwind CSS configured. Add the A2UI React components to your `tailwind.config.js`:
+
+```js
+module.exports = {
+  content: [
+    // ... your content paths
+    "./node_modules/@a2ui/react/**/*.{js,ts,jsx,tsx}",
+  ],
+  // ... rest of config
+};
+```
+
+### 2. Wrap your app with providers
+
+```tsx
+import { A2UIProvider, ThemeProvider } from "@a2ui/react";
+
+function App() {
+  const handleAction = (action) => {
+    // Send action to your server
+    console.log("Action:", action);
+  };
+
+  return (
+    <A2UIProvider onAction={handleAction}>
+      <ThemeProvider>
+        <YourApp />
+      </ThemeProvider>
+    </A2UIProvider>
+  );
+}
+```
+
+### 3. Process messages and render
+
+```tsx
+import { useA2UI, A2UIRenderer } from "@a2ui/react";
+import { useEffect } from "react";
+
+function YourApp() {
+  const { processMessages } = useA2UI();
+
+  useEffect(() => {
+    // Fetch A2UI messages from your server
+    fetch("/api/a2ui")
+      .then((res) => res.json())
+      .then((messages) => processMessages(messages));
+  }, [processMessages]);
+
+  return <A2UIRenderer surfaceId="main" />;
+}
+```
+
+## API Reference
+
+### Providers
+
+#### `<A2UIProvider>`
+
+Main context provider for A2UI state management.
+
+```tsx
+<A2UIProvider onAction={(action) => console.log(action)}>
+  {children}
+</A2UIProvider>
+```
+
+Props:
+- `onAction`: Callback when user triggers an action (e.g., button click)
+- `children`: React children
+
+#### `<ThemeProvider>`
+
+Provides CSS class mappings for styling components.
+
+```tsx
+<ThemeProvider theme={customTheme}>
+  {children}
+</ThemeProvider>
+```
+
+Props:
+- `theme`: Optional custom theme object (defaults to ShadCN-style theme)
+- `children`: React children
+
+### Hooks
+
+#### `useA2UI()`
+
+Main hook for interacting with A2UI.
+
+```tsx
+const {
+  surfaces,          // Map of all surfaces
+  getSurface,        // Get a specific surface
+  processMessages,   // Process incoming A2UI messages
+  sendAction,        // Send an action to the server
+  getComponentTree,  // Get the root component tree for a surface
+  clearSurfaces,     // Clear all surfaces
+} = useA2UI();
+```
+
+#### `useDataBinding(node, surfaceId)`
+
+Hook for resolving data bindings in custom components.
+
+```tsx
+const {
+  resolveString,   // Resolve a StringValue
+  resolveNumber,   // Resolve a NumberValue
+  resolveBoolean,  // Resolve a BooleanValue
+  setValue,        // Set a value in the data model
+  getValue,        // Get a value from the data model
+} = useDataBinding(node, surfaceId);
+```
+
+### Components
+
+#### `<A2UIRenderer>`
+
+Main renderer component that renders an entire A2UI surface.
+
+```tsx
+<A2UIRenderer
+  surfaceId="main"
+  className="my-surface"
+  fallback={<Loading />}
+/>
+```
+
+Props:
+- `surfaceId`: The ID of the surface to render
+- `className`: Optional CSS class for the root element
+- `fallback`: Optional fallback when surface is not found
+
+### Standard Components
+
+All 18 standard A2UI components are implemented:
+
+**Content:**
+- `Text` - Text with markdown support and typography hints
+- `Image` - Images with fit and usage hints
+- `Icon` - Icons from Lucide React
+- `Video` - Video player
+- `AudioPlayer` - Audio player with description
+- `Divider` - Horizontal/vertical separator
+
+**Layout:**
+- `Row` - Horizontal flex container
+- `Column` - Vertical flex container
+- `List` - Scrollable list (horizontal/vertical)
+- `Card` - Card container
+- `Tabs` - Tab navigation
+- `Modal` - Modal dialog
+
+**Interactive:**
+- `Button` - Clickable button with action support
+- `CheckBox` - Checkbox with label
+- `TextField` - Text input (various types)
+- `DateTimeInput` - Date/time picker
+- `MultipleChoice` - Select dropdown
+- `Slider` - Range slider
+
+## Custom Theming
+
+You can customize the appearance by providing a custom theme:
+
+```tsx
+import { ThemeProvider, defaultTheme } from "@a2ui/react";
+
+const customTheme = {
+  ...defaultTheme,
+  components: {
+    ...defaultTheme.components,
+    Button: {
+      "bg-blue-500": true,
+      "text-white": true,
+      "px-4": true,
+      "py-2": true,
+      "rounded": true,
+    },
+  },
+};
+
+<ThemeProvider theme={customTheme}>
+  {children}
+</ThemeProvider>
+```
+
+## Streaming Messages
+
+For streaming A2UI messages (e.g., from Server-Sent Events):
+
+```tsx
+function StreamingApp() {
+  const { processMessages } = useA2UI();
+
+  useEffect(() => {
+    const eventSource = new EventSource("/api/a2ui/stream");
+
+    eventSource.onmessage = (event) => {
+      const message = JSON.parse(event.data);
+      processMessages([message]);
+    };
+
+    return () => eventSource.close();
+  }, [processMessages]);
+
+  return <A2UIRenderer surfaceId="main" />;
+}
+```
+
+## TypeScript
+
+This package is written in TypeScript and includes full type definitions. Types are re-exported from `@a2ui/lit`:
+
+```tsx
+import { Types, Primitives, Data } from "@a2ui/react";
+
+// Use types
+const surface: Types.Surface = ...;
+const message: Types.ServerToClientMessage = ...;
+```
+
+## License
+
+Apache-2.0