Function makeTextLabelAtlas

makeTextLabelAtlas(
labels: readonly string[],
style?: TextLabelStyle,
): { atlas: BillboardSpriteAtlas; indexOf: Map<string, number> }
Build a billboard atlas of text labels, one cell per UNIQUE label string. Browser-only (Canvas 2D).
Parameters
- labels: readonly string[]
  The label strings to rasterise (duplicates are deduped to one cell).
- style: TextLabelStyle = {}
  Text style (TextLabelStyle); each field falls back to a sensible default.
Returns { atlas: BillboardSpriteAtlas; indexOf: Map<string, number> }
{ atlas, indexOf } — the BillboardSpriteAtlas to feed a billboard renderer, and a label → cell index map so a caller can set each point's symbolId.
Example
```
const { atlas, indexOf } = makeTextLabelAtlas(['Oak', 'Birch', 'Pine']);
map.addLayer(new BillboardInstancesLayer({
  id: 'species', atlas,
  instances: trees.map((t) => ({ position: t.pos, symbolId: indexOf.get(t.species)! })),
}));
```