🎨 Palette: Enhanced Keyboard Shortcut Instructions

[EiJackGH]

• 💡 What: Wrapped keyboard shortcuts in semantic <kbd> tags and applied physical key styling. Appended custom CSS to the internal <style> block to maintain consistency with the existing file pattern.
• 🎯 Why: Improves intuitiveness and discoverability by visually distinguishing interactive key commands from regular instructional text.
• 📸 Before/After: "Press Space or ↑ to jump!" -> "Press [Space] or [↑] to jump!" (styled like physical keys).
• ♿ Accessibility: Provides semantic meaning to keyboard shortcuts and ensures high visual contrast against the dynamic game background.

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PR created automatically by Jules for task 5432699396585877942 started by @EiJackGH

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