feat: OpenAI realtime API support

- [x] I have looked for existing issues (including closed) about this

## Feature Request
Add support for the realtime WebRTC and Websocket connection to the realtime API

### Motivation
Agents that use the realtime API

### Proposal

### Alternatives

The issue mentions adding support for OpenAI's realtime API via WebRTC and WebSocket connections. Look for existing API client code in the repository to understand the current integration patterns. Research the OpenAI realtime API documentation to identify required endpoints, authentication, and data formats. Determine how WebRTC/WebSocket connections should be managed within the Rust application's architecture, likely involving async networking and state handling.

索引モデルが issue の本文から書いたものです。