feat: add bidirectional translation support

[liujianqiang-niu]

Enhanced translation functionality to support both Chinese-to-English and English-to-Chinese translation directions
Added command-line options --to-english and --to-chinese for explicit direction control
Implemented configurable default translation direction via config command
Updated translation prompts for different directions with specific formatting rules
Added text wrapping for Chinese content to maintain proper formatting Modified AI service interface to accept translation direction parameter Updated documentation with new features and examples

Log: Added bidirectional translation support with configurable direction

Influence:

1. Test Chinese-to-English translation with various Chinese text inputs
2. Test English-to-Chinese translation with different English content
3. Verify translation direction configuration persistence
4. Test command-line options for explicit translation direction control
5. Validate translation quality and format preservation
6. Test mixed content handling (Chinese and English in same text)
7. Verify configuration settings for default translation direction

feat: 添加双向翻译支持

增强翻译功能，支持中译英和英译中双向翻译
添加命令行选项 --to-english 和 --to-chinese 用于显式控制翻译方向
实现可通过配置命令设置默认翻译方向
为不同翻译方向更新提示词，包含特定的格式规则
添加中文文本自动换行以保持格式规范
修改 AI 服务接口以接受翻译方向参数
更新文档，包含新功能和示例

Log: 新增双向翻译支持，可配置翻译方向

Influence:

1. 测试中译英功能，使用各种中文文本输入
2. 测试英译中功能，使用不同英文内容
3. 验证翻译方向配置的持久性
4. 测试命令行选项的显式翻译方向控制
5. 验证翻译质量和格式保持
6. 测试混合内容处理（中英文混合文本）
7. 验证默认翻译方向的配置设置

Fixes: #16