feat(core): asynchronous view resolution - #10865

Note

Medium Risk
Changes core Deck initialization ordering and layer lifecycle timing; apps or tests that assumed an immediate default viewport may need to activate one explicitly.

Overview
Adds asynchronous view resolution so layers are not initialized or updated until a real viewport exists, paving the way for views that load projection resources before makeViewport() can succeed.

View API: optional initialize() (sync or async); makeViewport() may return null while initialization is pending. ViewManager starts initialization for new views, reuses prior view instances when props are equal (preserving in-flight init), exposes updateViewports() for deferred rebuilds, forwards init failures via onError (wired from Deck’s props.onError), and skips controllers when no viewport is available.

LayerManager: removes the synthetic default viewport; context.viewport is null until activateViewport runs. setLayers / updateLayers no-op until a viewport is set, queueing the latest layer list. When a viewport first becomes available, existing layers get viewportChanged / projectionChanged and a full update is scheduled.

Deck calls viewManager.updateViewports() each frame before layerManager.updateLayers(), refreshing the active viewport when async views finish.

Tests and harnesses now pass an explicit viewport into LayerManager, with new coverage for deferred layers and async/partial view failure.

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