Update documentation to reflect rebranding from AI Video Assistant to Realtime Agent Studio (RAS)

- Changed site name and description in mkdocs.yml.
- Revised content in index.md to provide a comprehensive overview of RAS features and capabilities.
- Updated API reference and error documentation to replace AI Video Assistant with RAS.
- Modified deployment and getting started guides to align with the new branding.
- Enhanced quickstart instructions to specify RAS service requirements.

docs/content/getting-started/index.md

@@ -1,10 +1,10 @@
 # 安装部署
 
-本章节介绍如何安装和配置 AI Video Assistant 开发环境。
+本章节介绍如何安装和配置 Realtime Agent Studio (RAS) 开发环境。
 
 ## 概述
 
-AI Video Assistant 由以下组件构成：
+Realtime Agent Studio (RAS) 由以下组件构成：
 
 | 组件 | 说明 |
 |------|------|