Tasks

1. Show/hide contact details on hover

Hint using state and a callback, not CSS.

2. Add ability to filter contacts by name

3. Add button that keeps the contact expanded

4. Filter by all fields, not just name

5. Make filtering case insensitive

6. Add button that sorts contacts by name; clicking the button should toggle sort direction

7. Add an icon the the button (↑/↓) to indicate sorting direction.