feat: add CLI settings export/import functionality

- Implemented exportSettings and importSettings APIs for CLI settings.
- Added hooks useExportSettings and useImportSettings for managing export/import operations in the frontend.
- Updated SettingsPage to include buttons for exporting and importing CLI settings.
- Enhanced backend to handle export and import requests, including validation and conflict resolution.
- Introduced new data structures for exported settings and import options.
- Updated localization files to support new export/import features.
- Refactored CLI tool configurations to remove hardcoded model defaults, allowing dynamic model retrieval.

ccw/frontend/src/components/terminal-dashboard/CliConfigModal.tsx

@@ -129,7 +129,9 @@ export function CliConfigModal({
     const toolConfig = cliTools[tool];
     if (!toolConfig) return [];
     if (toolConfig.availableModels?.length) return toolConfig.availableModels;
-    const models = [toolConfig.primaryModel];
+    // Build models from primaryModel/secondaryModel, filtering out undefined
+    const models: string[] = [];
+    if (toolConfig.primaryModel) models.push(toolConfig.primaryModel);
     if (toolConfig.secondaryModel && toolConfig.secondaryModel !== toolConfig.primaryModel) {
       models.push(toolConfig.secondaryModel);
     }