Function renderShadow

renderShadow(
    builder: DrawlistBuilderV1,
    rect: Rect,
    config: ShadowConfig,
    baseStyle: ResolvedTextStyle,
): void
Render a shadow behind a rectangle.

Call this BEFORE rendering the box content to ensure the shadow appears behind the box.

The shadow is drawn to the right and below the box, creating a drop shadow effect.
Parameters
- builder: DrawlistBuilderV1
  Drawlist builder
- rect: Rect
  The rectangle to cast shadow from
- config: ShadowConfig
  Shadow configuration
- baseStyle: ResolvedTextStyle
  Base style to get background color from
Returns void
Example
```
// Render shadow first
renderShadow(builder, { x: 5, y: 2, w: 20, h: 10 }, DEFAULT_SHADOW, baseStyle);

// Then render the box on top
renderBoxBorder(builder, rect, "rounded", ...);
```
- Defined in core/src/renderer/shadow.ts:98