Historical price data: add chart UI and increase default data points

[premiumjibles]

Problem

"Get price data on past 24 hours" — backend works but results dump as plain text. Two gaps:

tk ticket: sa-lurv

1. No UI component — every other market data tool has a *UI.tsx card, but getHistoricalPrices does not
2. Default dataPoints=2 is too sparse — returns just start/end values instead of a meaningful time series for 24h

Fix

1. Create HistoricalPricesUI.tsx with a price chart (sparkline or line chart). Will need a lightweight chart library (recharts, lightweight-charts) or custom SVG sparkline — no chart library exists in the project yet.
2. Increase default dataPoints for short ranges (≤7 days → 24 points for hourly resolution)
3. Update system prompt to guide LLM to request more data points for recent ranges

Key Files

• apps/agentic-server/src/tools/getHistoricalPrices.ts
• apps/agentic-server/src/lib/asset/coingecko/api.ts
• apps/agentic-chat/src/components/tools/ (new UI component)

Acceptance Criteria

• HistoricalPricesUI renders visual price chart for returned data points
• 24h queries return enough data points for meaningful chart
• Percent change and start/end prices clearly displayed
• Multiple assets render comparison view