Mastermind

[stellaappiok]

This adds a terminal-based implementation of the classic Mastermind code-breaking game.
What it does

• Generates a random secret 4-color code from a set of 6 colors
• Lets the player guess the code (space-separated colors) over up to 10 tries
• Scores each guess with correct-position and incorrect-position counts, correctly handling duplicate colors so a color isn't double-counted across both checks
• Ends when the player guesses correctly or runs out of tries (revealing the code)

Why
A simple, dependency-free logic game that's a good example of input validation and a non-trivial scoring algorithm (handling repeated colors properly is the classic Mastermind gotcha).
How to test

1. Run python mastermind.py
2. Try a few guesses with invalid input (wrong length, invalid color letters) to confirm validation messages appear
3. Play a full round to confirm scoring feedback and win/lose conditions behave as expected, including guesses with repeated colors (e.g. code has one R but your guess has two)

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