phsl / new-api

- Create new CodeViewer component with VS Code dark theme styling
- Implement custom JSON syntax highlighting with proper color coding
- Add improved copy functionality with hover effects and user feedback
- Refactor DebugPanel to use the new CodeViewer component
- Apply dark background (#1e1e1e) with syntax colors matching VS Code
- Enhance UX with floating copy button and responsive design
- Support automatic JSON formatting and parsing
- Maintain compatibility with existing Semi Design components

The debug panel now displays preview requests, actual requests, and
responses in a professional code editor style, improving readability
and developer experience in the playground interface.