Smiley Face Part 1
A smiling face rendered as a yellow circle with black outline, two eyes, and an arc-shaped mouth. Built with React components for the background circle, eyes, and mouth, the SVG is centered via a `<g>` transform. The mouth uses `d3.arc` with inner and outer radii and start/end angles, while eye positions and radii derive from constants. The visualization demonstrates composable React-D3 integration, with all geometry defined as reusable props-driven components.