FluentAnnotationOnlyChart class

A chart made of annotations alone: no axes, no legend, no marks.

The package exports it and the annotations layer requires it, even though the storybook sidebar omits it. It exists because the Plotly adapter produces figures whose only content is annotations (AnnotationOnlyChart.types.ts:14, :22, :30).

Every annotation whose coordinates resolve in data space is dropped: the context supplies no scales (AnnotationOnlyChart.tsx:139-143), so resolveDataCoordinate returns nothing and the layer skips the annotation silently. Only relative and pixel coordinates render here.

Upstream's two-pass measure — an unmeasured annotation is laid out at 180 x 60 on the first frame and snaps once a hidden measurement div reports (ChartAnnotationLayer.tsx:446-467, :535-536, :607-633) — has no analogue here, because FluentChartAnnotationLayer measures its children synchronously during layout. The 180 x 60 fallback and the JSON measurement-signature cache are therefore both absent.