🎨 Palette: Add empty state for personal best score

[EiJackGH]

• What: Added an explicit "None yet! Set a record!" empty state for the personal best display when the high score is 0.
• Why: Previously, the high score display was hidden entirely for first-time players. Adding an explicit empty state clarifies the game's goal and encourages new users to play.
• Before/After: Before, nothing was displayed. After, an encouraging message is shown.
• Accessibility: Improves cognitive accessibility by clearly stating the objective rather than relying on implied absence.

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PR created automatically by Jules for task 12715763142377225400 started by @EiJackGH

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