🎨 Palette: Add keyboard instructions and ARIA attributes to Mario game

[EiJackGH]

💡 What:
Added visible keyboard instructions ("Press Space or ↑ to jump") to the top right of the game container. Also added aria-live="polite" and aria-atomic="true" to the score container. Additionally, I removed venv from requirements.txt to fix pip installations.

🎯 Why:
Users need to know what keys to press to interact with the game. Without instructions, the custom keybindings are a guess.

📸 Before/After:
Before: The top right was empty and the score wasn't announced.
After: The top right has "Press Space or ↑ to jump" with a semi-transparent dark background.

♿ Accessibility:
The new ARIA attributes ensure that screen readers will correctly read out the dynamic score when it is updated. The explicit visible instructions help users with cognitive or interactive needs know how to play.

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PR created automatically by Jules for task 7637536614692917530 started by @EiJackGH

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