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/stores/configStore.ts

@@ -14,40 +14,30 @@ import type {
   A2UIPreferences,
 } from '../types/store';
 
-// Default CLI tools configuration
+// Default CLI tools configuration - no model defaults, models come from user's cli-tools.json
 const defaultCliTools: Record<string, CliToolConfig> = {
   gemini: {
     enabled: true,
-    primaryModel: 'gemini-2.5-pro',
-    secondaryModel: 'gemini-2.5-flash',
     tags: ['analysis', 'debug'],
     type: 'builtin',
   },
   qwen: {
     enabled: true,
-    primaryModel: 'coder-model',
-    secondaryModel: 'coder-model',
     tags: [],
     type: 'builtin',
   },
   codex: {
     enabled: true,
-    primaryModel: 'gpt-5.2',
-    secondaryModel: 'gpt-5.2',
     tags: [],
     type: 'builtin',
   },
   claude: {
     enabled: true,
-    primaryModel: 'sonnet',
-    secondaryModel: 'haiku',
     tags: [],
     type: 'builtin',
   },
   opencode: {
     enabled: true,
-    primaryModel: 'opencode/glm-4.7-free',
-    secondaryModel: 'opencode/glm-4.7-free',
     tags: [],
     type: 'builtin',
   },