refactor(ai-plugin): Remove frontend code and restructure AI plugin architecture

- Remove AIAssistant.vue from main project frontend
- Clean up AI assistant UI integration from StoreManager.vue
- Maintain backend AI client infrastructure (ai_client.go, ai_manager.go)
- Preserve gRPC client implementation for AI plugin communication
- Update project architecture to separate frontend/backend concerns

Breaking Changes:
- Frontend AI assistant interface removed from main project
- AI plugin frontend code should be developed independently in plugin repository

Technical Details:
- Deleted: console/atest-ui/src/views/AIAssistant.vue
- Modified: Removed AI assistant entry points from StoreManager.vue
- Preserved: pkg/server/ai_client.go (gRPC client implementation)
- Preserved: pkg/server/ai_manager.go (AI service management)
- Maintained: Backend API architecture for AI plugin integration

Architecture Impact:
- Frontend code separation: AI plugin UI should be in plugin repo's ui/ directory
- Backend integration maintained: gRPC communication layer preserved
- Resource embedding: AI plugin will serve frontend assets via gRPC endpoints
- Build process: Frontend assets will be embedded in plugin binary
- Refactor the AI client and manager code, replacing the custom AIRequest and AIResponse types with those generated by protobuf. Modified request processing logic to accommodate the new type structure and updated metadata field types. Also fixed formatting issues in the code

Next Steps:
- AI plugin repository should implement independent frontend in ui/ directory
- Frontend assets will be served via GetPageOfJS() and GetPageOfCSS() gRPC methods
- Main project will consume AI frontend through plugin's resource endpoints

Author: KariHall619