feat(ui): dashboard — PercentileRow component

[Tinna23]

Overview

Build the PercentileRow component — a horizontal strip displaying all eleven percentile fee values from the latest Horizon data.

Acceptance Criteria

• Component at src/app/components/dashboard/PercentileRow.tsx
• Accepts props: { percentiles: PercentileFees | null; isLoading: boolean }
• Displays all eleven percentiles in order: p10 p20 p30 p40 p50 p60 p70 p80 p90 p95 p99
• Each cell: percentile label above, value in stroops below
• Colour gradient from green (low) to yellow/red (high) to visually convey distribution
• Scrollable horizontally on small screens
• Loading state: skeleton cells
• Values sourced directly from FeeStats.percentiles (the corrected Horizon field mapping)

Notes

• The percentile fields (p10–p99) come from the backend which maps Horizon's non-standard response fields — do not assume p25/p75 exist