Add level of difficulty for users to choose from

[aditi04menon]

Allow users to choose level of difficulty for the game from easy, medium, hard

[gisellemcneill]

If possible, when adding new questions, maybe we need to move the location of the questions into a new file since we will need to add 3 times the number of questions.

[audreysimonnet]

As a player, I want to be able to choose a difficulty level after selecting a category and receive questions that match that difficulty, so that I can tailor the trivia game to my skill level.

Input: user clicks category button, bot presents difficulty buttons, user clicks one
Output: bot confirms difficulty selection, only serves questions matching the chosen category and difficulty for the round

Value: improves replayability, makes the game more competitive

Functional Acceptance Criteria: difficulty buttons appear immediately after category selection, if the user doesn't select within 30 seconds the game ends early, game correctly displays questions from the category and difficulty, each category has 15 questions per difficulty
Non-Functional Criteria: colored buttons to distinguish between difficulties (easy - green, medium - blue, hard - red), confirmation message is short and clear

Story Points: 4