🎨 Palette: Add keyboard hint and ARIA live region to game score

[EiJackGH]

💡 What:
Added aria-live="polite" and aria-atomic="true" to the score counter in the Mario Game. Additionally, an on-screen text hint was added below the score to explicitly inform players of the keyboard controls ("Press Space or Up Arrow to jump"). Also cleaned up requirements.txt to remove venv which was causing pip install failures.

🎯 Why:
Dynamically updating text like a score counter needs ARIA attributes to be properly announced by screen readers without interrupting the user. The game also entirely lacked visible instructions for how to play; adding a persistent hint lowers the barrier to entry and cognitive load for new users.

📸 Before/After:
Before:
Score counter was visually updated but silent to assistive technologies. No keyboard controls were shown.

After:
Score updates are announced. A clear textual hint is positioned visibly at the top left.

♿ Accessibility:

• Applied aria-live="polite" to #score so that screen readers announce the changing number as the game progresses.
• Added explicit keyboard control hints so users aren't left guessing which keys trigger actions.

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PR created automatically by Jules for task 15070201797901690005 started by @EiJackGH

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