🎨 Palette: Add explicit empty state for zero high score

[EiJackGH]

💡 What: Replaced the hidden high score behavior with a visible, encouraging empty state when the score is 0.
🎯 Why: Hiding UI elements when data is empty makes the system state less clear. Providing an explicit empty state acts as a subtle onboarding tool and encourages initial interaction.
📸 Before/After: Before, a new player saw nothing below the game title. Now, they see "Personal Best: None yet! (Play to set one!)".
♿ Accessibility: Improves cognitive accessibility by clearly defining the system state rather than relying on absence to convey meaning.

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PR created automatically by Jules for task 8529570251847165073 started by @EiJackGH

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