Reusable D3 Scatter Plot
This reusable scatter plot displays the Iris Dataset, mapping petal length against sepal length for three species of iris flowers. The visualization uses D3’s `scaleLinear`, `scaleOrdinal`, `axisLeft`, `axisBottom`, `symbol`, and `symbols` APIs to render an SVG plot with distinct symbols for each species. The chart is built as a configurable D3 module via a `scatterPlot()` function, which accepts width, height, data, value accessors, margins, and radius as chainable options. Data is loaded asynchronously from a CSV file using `d3.csv`.