Add React Native Client to AG-UI

**Description:**

AG-UI currently provides client implementations for web and CLI environments, but lacks a dedicated React Native client. Given the increasing demand for integrating AI agents into mobile applications, adding a React Native client would enable developers to build native mobile applications that leverage AG-UI's event-driven protocol.

**Proposed Implementation:**

Transport Layer: Utilize React Native's networking capabilities to support connections for real-time event streaming.

Event Handling: Implement event listeners to handle AG-UI's event types, such as TEXT_MESSAGE_CONTENT, TOOL_CALL_START, and STATE_DELTA, updating the UI accordingly.

UI Components: Provide React Native components that render AG-UI events, allowing for a seamless integration of AI agents into mobile applications.

**Benefits:**

Native Performance: Leverage React Native's native components for optimal performance on mobile devices.

Real-Time Interaction: Enable real-time, bi-directional communication between AI agents and users, enhancing user experience.

Broad Adoption: Expand AG-UI's applicability to mobile developers, increasing its adoption and community support.