🎨 Palette: Clarify Basis Points in Transaction Cost Input

[aarjava]

This PR addresses a minor UX/accessibility issue by clarifying financial jargon in the interface.

💡 What: Added a help tooltip to the Transaction Cost (bps) input in src/dashboard.py.
🎯 Why: "Basis points" is a common financial term, but providing a concrete mathematical example directly in the UI (e.g., 10 bps = 0.10%) prevents cognitive friction and makes the configuration clearer.
♿ Accessibility: Improves content clarity by explaining specialized vocabulary inline.

Also created a journal entry in .Jules/palette.md to record this learning about clarifying financial/statistical parameters. Tested locally using pytest and verified the UI via a Playwright test.

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PR created automatically by Jules for task 10839483329896453915 started by @aarjava

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