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/vite-env.d.ts

@@ -28,7 +28,8 @@ declare global {
       getClaudeCodeConfigPath: () => Promise<string>;
       getClaudeConfigStatus: () => Promise<ConfigStatus>;
       getConfigStatus: (app?: AppType) => Promise<ConfigStatus>;
-      selectConfigFile: () => Promise<string | null>;
+      getConfigDir: (app?: AppType) => Promise<string>;
+      selectConfigDirectory: (defaultPath?: string) => Promise<string | null>;
       openConfigFolder: (app?: AppType) => Promise<void>;
       openExternal: (url: string) => Promise<void>;
       updateTrayMenu: () => Promise<boolean>;