Add a terminal spinner during LeetCode API calls

[dfayd0]

Enhance the user experience by adding a spinner animation in the terminal whenever the CLI makes calls to the LeetCode API. This will provide visual feedback to users that a network operation is in progress, improving usability—especially during potentially long waits for API responses.

Acceptance Criteria:

• Display a spinner in the terminal while waiting for responses from the LeetCode API.
• Ensure the spinner is cleared or stopped once the operation completes (success or error).
• The spinner should not interfere with any output or error messages.
• Prefer using a cross-platform library for the spinner if available.