🎨 Palette: Improve game responsiveness and visual feedback

[aidasofialily-cmd]

💡 What:

• Extracted UI rendering to a centralized render_ui function.
• Added ANSI color codes (Green for score, Bold Red for Hard Mode) and bold text.
• Replaced the busy-loop sleep_for with a dynamic poll() timeout for instant responsiveness.
• Improved the "Game Over" screen with a clear banner.
• Fixed Hard Mode toggle to update in-place instead of printing new lines.

🎯 Why:

• The game felt unresponsive because the score only updated on the 1-second tick, even if the user clicked.
• The interface was monochrome and cluttered when toggling modes.
• The busy loop was inefficient.

♿ Accessibility:

• Increased visual contrast using bold and colored text to highlight important game states (Score and Mode).
• Standardized the UI to a single-line update, making it easier for users to track changes without scanning multiple lines of scrolling text.

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PR created automatically by Jules for task 10107469518797870887 started by @aidasofialily-cmd

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