feat: 项目基础框架搭建 - Phase 1 Issue #1

- 创建 Cargo.toml 依赖配置
- 实现配置管理模块 (config/)
- 实现核心服务模块 (core/)
  - 文档处理引擎
  - 翻译服务
- 实现基础设施模块 (infrastructure/)
  - 存储模块
- 实现 UI 模块 (ui/)
- 集成 logging (tracing)

项目结构:
├── Cargo.toml
├── src/
│   ├── main.rs
│   ├── config/mod.rs
│   ├── core/
│   │   ├── mod.rs
│   │   ├── document.rs
│   │   └── translation.rs
│   ├── infrastructure/
│   │   ├── mod.rs
│   │   └── storage.rs
│   └── ui/
│       └── mod.rs

src/core/translation.rs

@@ -0,0 +1,30 @@
+//! 翻译服务模块
+
+use anyhow::Result;
+
+pub enum TranslationProvider {
+    Google,
+    DeepL,
+    Ollama,
+}
+
+pub struct TranslationService {
+    provider: TranslationProvider,
+    api_key: Option<String>,
+}
+
+impl TranslationService {
+    pub fn new(provider: TranslationProvider, api_key: Option<String>) -> Self {
+        Self { provider, api_key }
+    }
+    
+    pub fn translate(&self, text: &str, from: &str, to: &str) -> Result<String> {
+        // 后续实现：调用翻译 API
+        todo!("Implement translation for: {}", text)
+    }
+    
+    pub fn detect_language(&self, text: &str) -> Result<String> {
+        // 后续实现：语言检测
+        todo!("Implement language detection")
+    }
+}