Serve static files with a built-in HTTP server:

```vary
import http

http.serve("./public", port=3000, spa=True)
```

| **Function** | **Returns** | **Description** |
|----------|---------|-------------|
| `http.serve(directory, port?, host?, spa?)` | `None` | Start a blocking static file server |

Defaults: `port=4000`, `host="127.0.0.1"`, `spa=False`. SPA mode serves `index.html` for paths that don't match a file (for client-side routing). Supports HTML, CSS, JS, JSON, SVG, images, WASM, and more.