🎨 Palette: Add explicit empty state for high score

[EiJackGH]

💡 What: Replaced the hidden high score state with an explicit empty state ("None yet! Go set a record!") when the user has no existing high score.
🎯 Why: In terminal applications, users can be confused if an expected UI element is entirely absent. Providing an explicit, encouraging empty state clarifies the system state, improves onboarding, and prevents the interface from feeling broken or incomplete.
📸 Before/After:
Before: [Speed Clicker]
Controls: ...
After: [Speed Clicker]
Personal Best: None yet! Go set a record!
Controls: ...
♿ Accessibility: N/A - text clarity improvement.

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PR created automatically by Jules for task 1782947101465930121 started by @EiJackGH

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