awaitMapStyle

Persisted mapStyle; suspends for the first disk load to avoid a cold-start default.

mapStyle is shared eagerly and starts at 0 before the first disk read completes, same as hiddenLayerUrls's empty-set default. A caller that renders a basemap from the eager value before this resolves can render the wrong one and then swap moments later — which, for a MapLibre style, means tearing down and rebuilding the whole style subcomposition out from under sources still attaching to it.