🎨 Palette: Add help tooltips to financial parameters

[google-labs-jules]

💡 What: Added explanatory tooltips to 'High Volatility Quantile' and 'Transaction Cost' inputs in the sidebar. Also added matplotlib to requirements.txt to fix a runtime error.
🎯 Why: Users need context for statistical (quantiles) and financial (bps) parameters. The app was crashing due to missing matplotlib dependency for pandas styling.
♿ Accessibility: Improved clarity for non-expert users by providing concrete examples in tooltips.

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PR created automatically by Jules for task 9311584590990454045 started by @aarjava

[google-labs-jules]

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