feat: add config directory override support for WSL

- Add persistent app settings with custom Claude Code and Codex config directories
- Add config directory override UI in settings modal with manual input, browse, and reset options
- Integrate tauri-plugin-dialog for native directory picker
- Support WSL and other special environments where config paths need manual specification

Changes:
- settings.rs: Implement settings load/save and directory override logic
- SettingsModal: Add config directory override UI components
- API: Add get_config_dir and pick_directory commands

src-tauri/src/config.rs

@@ -6,6 +6,10 @@ use std::path::{Path, PathBuf};
 
 /// 获取 Claude Code 配置目录路径
 pub fn get_claude_config_dir() -> PathBuf {
+    if let Some(custom) = crate::settings::get_claude_override_dir() {
+        return custom;
+    }
+
     dirs::home_dir()
         .expect("无法获取用户主目录")
         .join(".claude")