Mouse Follower
A circular marker follows the mouse cursor across an SVG canvas, while a path traces the complete route of its movement. The visualization demonstrates unidirectional data flow in React with D3.js v5, using React state and Hooks (`useState`, `useCallback`) to handle mouse events and trigger re-renders. The path is built by collecting `clientX` and `clientY` coordinates on each `onMouseMove` event, and a reset button clears the trace back to the current cursor position. The SVG is rendered directly via React, with D3 providing the `path` utility for constructing the line string.