🎨 Palette: Add explicit empty state for highscore

[EiJackGH]

💡 What: Added an encouraging explicit empty state message ("Let's set a record!") for the initial highscore display instead of relying on a blank UI state when the highscore is 0.
🎯 Why: When displaying achievements or data points that are initially empty, leaving the UI blank can feel unwelcoming. Providing an explicit, encouraging empty state clarifies the system state and improves user onboarding by giving them a clear goal.
📸 Before/After: Before, no highscore line was shown on the first run. Now, Personal Best: 0 (Let's set a record!) is displayed.
♿ Accessibility: Improves cognitive accessibility by clearly defining the starting state and expectations for the user.

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PR created automatically by Jules for task 6432341050101653895 started by @EiJackGH

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