Implement Stream Redirection Support

[FerdinandSu]

Description / 功能描述

English:
Implement stream redirection functionality from MobileSuit .NET v4.5+ to allow users to redirect command input/output to files, enabling better integration with shell scripts and automation workflows.

中文:
实现 MobileSuit .NET v4.5+ 的流重定向功能，允许用户将命令输入/输出重定向到文件，从而更好地与shell脚本和自动化工作流集成。

Features / 功能特性

English:

• Output redirection: command args > output.txt (overwrite)
• Append redirection: command args >> log.txt (append)
• Input redirection: command < input.txt (read from file)
• Support for absolute and relative file paths
• Proper file handle management and cleanup
• UTF-8 encoding by default

中文:

• 输出重定向: command args > output.txt (覆盖)
• 追加重定向: command args >> log.txt (追加)
• 输入重定向: command < input.txt (从文件读取)
• 支持绝对路径和相对路径
• 正确的文件句柄管理和清理
• 默认使用UTF-8编码

Tech Stack / 技术栈

• Extend ParsingService to detect redirect operators / 扩展 ParsingService 检测重定向操作符
• Create FileIOHub wrapping file streams / 创建包装文件流的 FileIOHub
• Integration with SuitContext for IOHub swapping / 与 SuitContext 集成以交换IOHub

Difficulty & Time / 难度与时间

Difficulty / 难度: 🟡 Medium / 中等
Estimated Time / 预估时间: 3-5 days / 3-5天

Requirements / 要求

English:

• MUST follow MobileSuit .NET API (see .claude/MobileSuitFeatures.md Feature 对SuitContext部分进行了单元测试 #12)
• MUST handle file permission errors gracefully with clear error messages
• MUST properly close file handles to prevent resource leaks
• MUST support UTF-8 encoding with proper BOM handling
• PR MUST include:
  • Unit tests for all redirection types
  • Tests for error scenarios (permission denied, file not found, etc.)
  • Integration tests with real files
  • Documentation with examples

中文:

• 必须 遵循MobileSuit .NET API（参见 .claude/MobileSuitFeatures.md 功能 对SuitContext部分进行了单元测试 #12）
• 必须 优雅地处理文件权限错误，并提供清晰的错误消息
• 必须 正确关闭文件句柄以防止资源泄漏
• 必须 支持UTF-8编码，正确处理BOM
• PR 必须 包含：
  • 所有重定向类型的单元测试
  • 错误场景测试（权限拒绝、文件未找到等）
  • 真实文件的集成测试
  • 带示例的文档

Acceptance Criteria / 验收标准

• Parse >, >>, < operators in ParsingService / 在ParsingService中解析操作符
• Implement output redirection (>) / 实现输出重定向
• Implement append redirection (>>) / 实现追加重定向
• Implement input redirection (<) / 实现输入重定向
• Create/overwrite files for > operator / 为 > 操作符创建/覆盖文件
• Append to existing files for >> operator / 为 >> 操作符追加到现有文件
• Read input line-by-line for < operator / 为 < 操作符逐行读取输入
• Handle file path validation (exists, writable, etc.) / 处理文件路径验证
• Implement proper error handling / 实现正确的错误处理
• Ensure file handles are closed (use context managers) / 确保文件句柄关闭（使用上下文管理器）
• Support both absolute and relative paths / 支持绝对路径和相对路径
• Add comprehensive unit tests (80%+ coverage) / 添加全面的单元测试
• Add integration tests with real file I/O / 添加真实文件I/O的集成测试
• Update documentation / 更新文档

Reference / 参考

See .claude/MobileSuitFeatures.md Feature #12 for detailed specification.
详细规格请参见 .claude/MobileSuitFeatures.md 功能 #12。

Before Starting / 开始之前

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