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/config/mod.rs

@@ -0,0 +1,69 @@
+//! 配置管理模块
+
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Config {
+    pub theme: ThemeConfig,
+    pub reader: ReaderConfig,
+    pub translation: TranslationConfig,
+    pub storage: StorageConfig,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ThemeConfig {
+    pub mode: String,  // "light" or "dark"
+    pub font_size: u32,
+    pub font_family: String,
+    pub line_height: f32,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ReaderConfig {
+    pub default_format: String,
+    pub scroll_smooth: bool,
+    pub show_toc: bool,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct TranslationConfig {
+    pub provider: String,  // "google", "deepl", "ollama"
+    pub api_key: Option<String>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct StorageConfig {
+    pub library_path: String,
+    pub cache_path: String,
+}
+
+impl Default for Config {
+    fn default() -> Self {
+        Self {
+            theme: ThemeConfig {
+                mode: "light".to_string(),
+                font_size: 16,
+                font_family: "system".to_string(),
+                line_height: 1.5,
+            },
+            reader: ReaderConfig {
+                default_format: "pdf".to_string(),
+                scroll_smooth: true,
+                show_toc: true,
+            },
+            translation: TranslationConfig {
+                provider: "ollama".to_string(),
+                api_key: None,
+            },
+            storage: StorageConfig {
+                library_path: "./library".to_string(),
+                cache_path: "./cache".to_string(),
+            },
+        }
+    }
+}
+
+pub fn load() -> Config {
+    // 后续从文件加载配置
+    Config::default()
+}