🎨 Palette: Make score dynamic updates screen-reader friendly

[EiJackGH]

💡 What: Extracted the static "Score:" label from the dynamic score value in the mario-game.njk DOM.
🎯 Why: Previously, if aria-live was added to the entire #score div, screen readers would read "Score: 1", "Score: 2", "Score: 3", which is highly repetitive and annoying. By separating the dynamic number into its own aria-live span, the screen reader elegantly reads just the updated number.
📸 Before/After: Visually identical, but audibly much improved.
♿ Accessibility: Added an aria-live="polite" region specifically constrained to the dynamic numerical score value.

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PR created automatically by Jules for task 9106948828511065574 started by @EiJackGH

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