phsl / new-api

Completely restructured the Playground component from a 1437-line monolith
into a maintainable, modular architecture with 62.4% code reduction (540 lines).

**Key Improvements:**
- **Modular Architecture**: Extracted business logic into separate utility files
  - `utils/constants.js` - Centralized constant management
  - `utils/messageUtils.js` - Message processing utilities
  - `utils/apiUtils.js` - API-related helper functions
- **Custom Hooks**: Created specialized hooks for better state management
  - `usePlaygroundState.js` - Centralized state management
  - `useMessageActions.js` - Message operation handlers
  - `useApiRequest.js` - API request management
- **Code Quality**: Applied SOLID principles and functional programming patterns
- **Performance**: Optimized re-renders with useCallback and proper dependency arrays
- **Maintainability**: Implemented single responsibility principle and separation of concerns

**Technical Achievements:**
- Eliminated code duplication and redundancy
- Replaced magic strings with typed constants
- Extracted complex inline logic into pure functions
- Improved error handling and API response processing
- Enhanced code readability and testability

**Breaking Changes:** None - All existing functionality preserved

This refactor transforms the codebase into enterprise-grade quality following
React best practices and modern development standards.