🎨 Palette: Add accessibility attributes to Mario game score and keyboard hints

[EiJackGH]

💡 What:

• Added aria-live="polite" and aria-atomic="true" to the dynamic score counter.
• Added a visual text hint below the score (Press Space or Up Arrow to jump).
• Removed venv from requirements.txt to fix pip install failures during testing.

🎯 Why:

• Screen readers were previously unable to announce the changing score, leaving visually impaired users without feedback on their progress.
• New users lacked immediate visual discoverability of the game controls, relying solely on trial and error.
• The invalid venv dependency prevented automated and local test suites from running successfully.

📸 Before/After:

• Before: The score was a static <div> without ARIA roles, and the game canvas was empty besides the entities.
• After: The score includes live ARIA regions, and a helpful, subtle text hint is rendered below the score.

♿ Accessibility:

• The dynamic score updates will now be read aloud smoothly by screen readers without interrupting other tasks (due to polite).
• The keyboard hints ensure users know how to interact with the application without needing to guess.

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PR created automatically by Jules for task 9068865671237893915 started by @EiJackGH

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