🎨 Palette: Improve score readability and CLI visual polish

[aidasofialily-cmd]

🎨 Palette: Improve score readability and CLI visual polish

This PR enhances the "Speed Clicker" CLI game with several micro-UX improvements:

• Implemented formatWithCommas to add thousands separators to all score displays for better readability.
• Replaced manual space padding with the CLR_EOL (\033[K) ANSI sequence for cleaner, artifact-free terminal updates.
• Improved the HUD with consistent bold styling for both labels and values.
• Colorized the "NEW BEST!" message and added context (previous personal best) to the game-over screen.
• Added CLR_EOL to countdown and "GO!" prompts to ensure a clean visual transition.

Verified with make and verify_ux.py. Added unit tests for the formatting logic.

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PR created automatically by Jules for task 13687285192052533361 started by @aidasofialily-cmd

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