[USER STORY] Add input validation to WordGuessGame #25
Description
User Story
As a player, I want to be warned if my guess includes numbers or symbols so that I don’t waste attempts on invalid guesses.
Acceptance Criteria
- Only 5-letter alphabetic inputs are accepted.
- Invalid inputs are rejected with an appropriate message.
- Valid guesses proceed with the game.
Details
Update the WordGuessGame to reject inputs that contain numbers, punctuation, or are not exactly 5 letters.
Ensure invalid input does not count as an attempt.