feat: Open ChatSDK

[tomasyu985]

What type of PR is this?

feat: 新增Chat SDK功能模块

Check the PR title.

• This PR title match the format: <type>(optional scope): <description>
• The description of this PR title is user-oriented and clear enough for others to understand.
• Add documentation if the current PR requires user awareness at the usage level.

PR标题: feat(chat-sdk): 新增Chat SDK功能模块，支持第三方应用集成聊天功能

(Optional) Translate the PR title into Chinese.

中文标题: 功能(聊天SDK): 新增聊天SDK功能模块，支持第三方应用集成聊天功能

(Optional) More detailed description for this PR(en: English/zh: Chinese).

en:
This PR introduces a new Chat SDK module that enables third-party applications to integrate chat functionality. The SDK provides a comprehensive set of APIs for chat operations including message sending, file uploads, and real-time communication. Key features include:

• UMD/ES Module Support: Bundled resources available in both UMD and ES module formats
• CDN Integration: Resources accessible via public CDNs (jsDelivr, unpkg)
• TypeScript Support: Full TypeScript definitions for better development experience
• File Upload: Built-in file upload capabilities with drag-and-drop support
• Customizable UI: Flexible UI components that can be styled and customized
• npm Package: Published as @coze-studio/chat-app-sdk for easy integration

The SDK is designed to be lightweight, performant, and easy to integrate into existing applications.

zh:
本次PR新增了聊天SDK功能模块，使第三方应用能够集成聊天功能。SDK提供了一套完整的聊天操作API，包括消息发送、文件上传和实时通信。主要特性包括：

• UMD/ES模块支持: 提供UMD和ES模块两种格式的打包资源
• CDN集成: 资源可通过公共CDN（jsDelivr、unpkg）访问
• TypeScript支持: 完整的TypeScript定义，提供更好的开发体验
• 文件上传: 内置文件上传功能，支持拖拽上传
• 可定制UI: 灵活的UI组件，可进行样式定制
• npm包: 发布为@coze-studio/chat-app-sdk，便于集成

SDK设计轻量、高性能，易于集成到现有应用中。

(Optional) Which issue(s) this PR fixes:

相关Issue: 新增功能，无关联Issue