Build a GitHub user search tool that fetches a profile and displays the avatar, bio, repositories, and follower count.
The user types a GitHub username and clicks search. Fetch the profile data from the GitHub API and render a profile card with avatar, name, bio, followers, and public repos.
Handle loading and error states, showing a message if the username is not found.
Focus on making an API request and rendering the returned data cleanly.
Test with a real username and with an invalid one to verify error handling.
