🎨 Palette: Clean up dynamic terminal output via ANSI Erase in Line

[EiJackGH]

• 💡 What: Replaced the anti-pattern of hardcoded trailing spaces used to clear dynamic terminal output lines with the standard ANSI escape sequence \033[K (Erase in Line). This was updated in src/main.cpp for the countdown, "GO!" print, and the main game score output loop.
• 🎯 Why: Dynamically updating CLI lines via carriage return (\r) requires clearing previous longer strings. Padding with spaces is fragile and messy, leaving visual artifacts if the new string length is significantly shorter. Using \033[K immediately clears the line cleanly and deterministically.
• 📸 Before/After: No visual difference assuming the spaces were always perfectly long enough; however, under the hood, the UX is robust and artifact-free regardless of string length.
• ♿ Accessibility/UX: Improves general visual interactions and ensures clean screen redraws in the CLI environment, reducing cognitive load from potential UI glitches. Recorded this learning in .Jules/palette.md.

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PR created automatically by Jules for task 18187167964531317196 started by @EiJackGH

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