🎨 Palette: Add explicit keyboard instructions for Mario game jump mechanic

[EiJackGH]

💡 What: Added an explicit, visible instructional overlay ("Press Space or Up Arrow to jump") to the mario game view.
🎯 Why: Custom HTML5 interactive widgets often lack discoverability for their controls. This enhancement provides immediate clarity on how to interact with the game, removing the need for users to guess the keyboard bindings.
📸 Before/After: Before, the game only displayed the score and required guessing to jump. After, a semi-transparent dark box sits in the top-right corner to explain the controls.
♿ Accessibility: Kept the text visible to screen readers (removed aria-hidden) and ensured the new visual element does not block interactions (pointer-events: none).

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PR created automatically by Jules for task 17253742310562312582 started by @EiJackGH

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