React D3 Conditional Line Chart Practice
This example shows a time-series line chart of risk values against a “Time” axis, with points colored conditionally (green, amber, or red) based on their value and annotated with dashed threshold lines at 50 and 75. It loads CSV data via `useData` and `d3.csv`, scales it with `scaleTime` and `scaleLinear`, and draws SVG axes and marks using React components, `d3.line`, and `d3.format`. Tooltips appear via SVG `<title>` elements showing the formatted value as a percentage.