Add JSDoc documentation to all chart component props

[yuribodo]

Description

GaugeChart has thorough JSDoc comments with `@default` annotations on every prop, but the other 9 charts have bare interfaces with no documentation.

Example of good JSDoc (GaugeChart pattern)

```typescript
interface GaugeChartProps {
/** The current value to display on the gauge /
readonly value: number;
/* Minimum value on the gauge scale @default 0 /
readonly min?: number;
/* Color zones for the gauge arc */
readonly zones?: readonly GaugeZone[];
}
```

Tasks

• Add JSDoc to BarChart props
• Add JSDoc to LineChart props
• Add JSDoc to PieChart props
• Add JSDoc to RadarChart props
• Add JSDoc to ScatterPlot props
• Add JSDoc to StackedBarChart props
• Add JSDoc to Heatmap props
• Add JSDoc to FunnelChart props
• Add JSDoc to TreemapChart props
• Include `@default` annotations for all optional props

Why this matters

JSDoc enables IDE IntelliSense tooltips, which is critical for a "zero-config" developer experience. Users shouldn't need to read docs to understand props.