🎨 Palette: Add explicit empty state for high score

[EiJackGH]

What: Added an explicit empty state message ("None yet! Play to set one!") for the high score when it is 0, instead of hiding the high score display entirely.
Why: To clarify the system state for new players, letting them know that a high score feature exists and encouraging them to play.
Before/After: Before, the high score line was completely hidden if the score was 0. After, it explicitly shows that there is no high score yet.
Accessibility: Improves cognitive accessibility and onboarding by making the game's achievement system transparent from the start.

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PR created automatically by Jules for task 9244773722105002266 started by @EiJackGH

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