🎨 Palette: Add keyboard instructions and improve screen reader accessibility for Mario game score

[EiJackGH]

💡 What:

• Added a visual instructions overlay explaining how to jump in the Mario game.
• Split the score text into a static label and a dynamic score counter.
• Added aria-live="polite" and aria-atomic="true" to the dynamic score counter.
• Prevented the score text string "Score: X" from repeatedly updating with the static label in the dynamic logic, ensuring screen readers only read the changed number.

🎯 Why:

• New players had no visual cues on which keys to press to play the game.
• Screen reader users were previously unaware of score changes. With the update, only the specific numerical score change is announced, preventing repetitive text reads.

📸 Before/After:
Before: Only the score label "Score: X" is visible.
After: Includes a "Press Space or Up Arrow to jump" subtext overlay and functionally separates static and dynamic score elements in the DOM.

♿ Accessibility:
Implemented dynamic score updates exclusively inside an ARIA live region without static text pollution. Included clear instructional text for interactive inputs.

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PR created automatically by Jules for task 9912087964025133303 started by @EiJackGH

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