🎨 Palette: Add concrete examples to numeric input tooltips

[aarjava]

• 💡 What: Added help attributes to three sidebar widgets (adv_pct, vol_q_high, and bt_cost) in src/dashboard.py to provide concrete examples (e.g., "10 bps = 0.10%"). Added a corresponding learning entry to .Jules/palette.md.
• 🎯 Why: Abstract statistical or financial metrics (like basis points or quantiles) can be confusing. Providing real-world examples in tooltips makes the interface more intuitive and accessible, preventing input errors.
• 📸 Before/After: The inputs previously had no hover states. Now, they display small "?" icons that reveal helpful text on hover.
• ♿ Accessibility: Improves cognitive accessibility by providing immediate, context-sensitive documentation for complex inputs.

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PR created automatically by Jules for task 9367291085166450467 started by @aarjava

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