添加 Microsoft Outlook MSG 文件解析器

Add Microsoft Outlook MSG File Parser

功能描述 | Features

• 实现了 Microsoft Outlook MSG 文件格式的解析功能
  Implemented parsing functionality for Microsoft Outlook MSG file format
• 支持将 MSG 文件内容转换为 Spring AI Document 统一格式
  Support converting MSG file content to Spring AI Document unified format
• 完全兼容 Compound File Binary Format (CFB) 文件结构
  Full compatibility with Compound File Binary Format (CFB) file structure

技术实现 | Technical Implementation

• 新增 MsgEmailDocumentReader 实现 Spring AI 的 DocumentReader 接口
  Added MsgEmailDocumentReader implementing Spring AI's DocumentReader interface
• 采用流式处理方式读取 MSG 文件，避免内存溢出
  Implemented streaming processing for MSG files to prevent memory overflow
• 实现了完整的错误处理和日志记录机制
  Implemented comprehensive error handling and logging mechanism
• 提供优雅的资源关闭处理
  Provided elegant resource cleanup handling

主要类说明 | Core Classes

• MsgEmailDocumentReader: MSG 文件核心解析器类
  Core parser class for MSG files
• MsgParser: MSG 文件结构解析器
  MSG file structure parser
• MsgEmailElement: MSG 邮件元素数据模型
  Data model for MSG email elements
• MsgEmailParser: 邮件内容解析和转换工具
  Email content parsing and conversion utility

测试覆盖 | Test Coverage

• 添加了单元测试类 MsgEmailDocumentReaderTest
  Added unit test class MsgEmailDocumentReaderTest
• 包含异常场景测试用例
  Included test cases for exception scenarios
• 提供测试资源文件
  Provided test resource files

依赖说明 | Dependencies

• 基于 Spring AI 框架
  Based on Spring AI framework
• 使用 Apache Commons IO 工具库
  Using Apache Commons IO utility library
• 使用 SLF4J 日志框架
  Using SLF4J logging framework

fixes #293