bgra8unorm-storage

The preferred canvas format on many platforms is bgra8unorm, but base WebGPU only guarantees storage writes for rgba8unorm. This feature closes the gap, letting compute shaders write directly into a texture you can present or copy cheaply, instead of writing RGBA and swizzling or blitting.

Compute-based post-processing, GPU video pipelines, and UI compositors are the typical beneficiaries: one less full-screen copy per frame. Availability is high on desktop; on platforms where the preferred format is already rgba8unorm the feature matters less.