🎨 Palette: Add explicit instructional hints for game controls

[EiJackGH]

💡 What: Added an explicit text hint ("Press Space or Up Arrow to jump") as a floating overlay to the Mario mini-game canvas in src/views/mario-game.njk.
🎯 Why: Custom keyboard bindings built into interactive HTML5 components (like mini-games) are not discoverable. Users shouldn't have to mash their keyboards to figure out how to play. This significantly improves the out-of-the-box user experience.
📸 Before/After: Before, the game only showed a score and sprite, leaving users guessing controls. Now, clear pulsating text indicates the correct controls.
♿ Accessibility: The text is visually distinct, animated gently to capture attention, and uses pointer-events: none to ensure it does not break or block native interaction on the container.

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PR created automatically by Jules for task 2431987870699077244 started by @EiJackGH

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