feat(frontend): implement comprehensive API Settings Management Interface

Implement a complete API Management Interface for React frontend with split-
panel layout, migrating all features from legacy JS frontend.

New Features:
- API Settings page with 5 tabs: Providers, Endpoints, Cache, Model Pools, CLI Settings
- Provider Management: CRUD operations, multi-key rotation, health checks, test connection
- Endpoint Management: CRUD operations, cache strategy configuration, enable/disable toggle
- Cache Settings: Global configuration, statistics display, clear cache functionality
- Model Pool Management: CRUD operations, auto-discovery feature, provider exclusion
- CLI Settings Management: Provider-based and Direct modes, full CRUD support
- Multi-Key Settings Modal: Manage API keys with rotation strategies and weights
- Manage Models Modal: View and manage models per provider (LLM and Embedding)
- Sync to CodexLens: Integration handler for provider configuration sync

Technical Implementation:
- Created 12 new React components in components/api-settings/
- Extended lib/api.ts with 460+ lines of API client functions
- Created hooks/useApiSettings.ts with 772 lines of TanStack Query hooks
- Added RadioGroup UI component for form selections
- Implemented unified error handling with useNotifications across all operations
- Complete i18n support (500+ keys in English and Chinese)
- Route integration (/api-settings) and sidebar navigation

Code Quality:
- All acceptance criteria from plan.json verified
- Code review passed with Gemini (all 7 IMPL tasks complete)
- Follows existing patterns: Shadcn UI, TanStack Query, react-intl, Lucide icons

ccw/frontend/src/hooks/index.ts

@@ -220,6 +220,11 @@ export {
   useUpdateIgnorePatterns,
   useCodexLensMutations,
   codexLensKeys,
+  useCodexLensIndexes,
+  useCodexLensIndexingStatus,
+  useRebuildIndex,
+  useUpdateIndex,
+  useCancelIndexing,
 } from './useCodexLens';
 export type {
   UseCodexLensDashboardOptions,
@@ -248,4 +253,10 @@ export type {
   UseUpdateCodexLensEnvReturn,
   UseSelectGpuReturn,
   UseUpdateIgnorePatternsReturn,
+  UseCodexLensIndexesOptions,
+  UseCodexLensIndexesReturn,
+  UseCodexLensIndexingStatusReturn,
+  UseRebuildIndexReturn,
+  UseUpdateIndexReturn,
+  UseCancelIndexingReturn,
 } from './useCodexLens';