* feat: enhance ThemeDropdown with keyboard navigation and improved layout
- Added keyboard navigation support for theme selection.
- Refactored theme selection UI to improve accessibility and user experience.
- Updated styles for better responsiveness and visual clarity.
- Consolidated theme rendering logic for light and dark themes.
* style: update ThemeDropdown styles for focus and active states
- Removed outline styles for focused states to enhance visual clarity.
- Adjusted background and border colors for active state to improve accessibility and user experience.
