🎨 Palette: Add explicit empty state for high score

[EiJackGH]

💡 What: Added an explicit empty state ("None yet! Set a record!") for the initial high score display, replacing the logic that completely hid the high score UI element when the score was 0.
🎯 Why: When a user first opens the application, hiding uninitialized UI elements leaves them without context about what features and achievements are possible. Providing an explicit, encouraging empty state clarifies the system state and improves user onboarding.
📸 Before/After: Before, a new user saw no "Personal Best" section. Now, a new user sees "Personal Best: None yet! Set a record!".
♿ Accessibility: Improves cognitive accessibility by providing immediate, explicit context about the application's features and state to new users.

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PR created automatically by Jules for task 13422434534575408753 started by @EiJackGH

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