Building the 2-panel interactive UI

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Objective: Implement the described layout: top movers chart panel + click-through “What’s the story?” panel.

Acceptance criteria:
• Top panel lists top 10/20 movers with interactive line charts (last 7d)
• Clicking a market updates the bottom panel (or scrolls to it) with title, platforms, latest prob, delta, and headlines list
• Filters: window selector (24h vs 7d) + platform toggle (Kalshi/Polymarket/both)