Description: - Add a button to the country card that marks or unmarks the country as a favorite. Tasks: - Create a dedicated FavoriteButton component. - Show the difference between an active and inactive favorite. - Use text or an accessible name in addition to the icon. - Pass status and callback through props. - Make the button keyboard-friendly. Acceptance: - The button adds and removes the correct country. - The favorite status is clear. - Screen readers get an understandable name and status. - The button works with the keyboard.