🎨 Palette: Add empty state for high score

[EiJackGH]

💡 What: Added an empty state for the personal best high score UI element when a user has no high score.
🎯 Why: Previously, the high score element was completely hidden if the score was 0. Showing an explicit empty state ("0 - Let's set a record!") clarifies to the user that a high score system exists and encourages them to participate.
📸 Before/After:
Before: UI element is absent if score is 0.
After: UI element displays "Personal Best: 0 - Let's set a record!" if score is 0.
♿ Accessibility: Provides clear system state visibility.

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PR created automatically by Jules for task 3421134533682547074 started by @EiJackGH

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