🎨 Palette: Add encouraging empty state for high score

[EiJackGH]

💡 What: Replaced the empty state behavior for the high score display. Instead of hiding the "Personal Best" section when the high score is 0, it now displays an encouraging message: "None yet! Set a record!".
🎯 Why: Hiding UI elements like "Personal Best" when there's no data leaves new users without context or a goal. Providing an explicit, encouraging empty state clarifies the system state, improves user onboarding, and gives them an immediate objective.
📸 Before/After:

• Before: (On first run, highscore 0) The "Personal Best" line was entirely missing.
• After: (On first run, highscore 0) Displays: Personal Best: None yet! Set a record!
  ♿ Accessibility: Improves cognitive accessibility by explicitly stating the game's goal and current state, rather than relying on the user to infer it from missing information.

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PR created automatically by Jules for task 13425118157128037546 started by @EiJackGH

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