Bubble Chart Visualization
This bubble chart visualizes the number of boba shops across California cities, with each circle’s area encoding the count. Circles start at the center and are arranged by a force simulation using `d3.forceSimulation`, including center, charge, and collide forces to prevent overlap. Users can drag circles, which temporarily fixes their position, and hover to see a tooltip with the city name and count via mouse events. The chart is rendered as SVG using D3 v7, with color from `d3.scaleOrdinal(d3.schemeSet3)`, and loads data from a CSV file.