Enumerating Vulkan adapters crashes inside Intel's igvk64.dll on some UHD
Graphics drivers, before any Rust error handling runs. Since #22 the
Windows instance is DirectX 12 only; this keeps Vulkan out of every
default path and adds two fallbacks so DX12-only can't leave a PC without
a window:
- A DirectX 12 probe before eframe starts: no hardware adapter that meets
eframe's limits -> OpenGL (plus DX12/WARP as last resort when WARP is
all DX12 offers).
- If run_native fails with a wgpu error before the app was created, start
once more with the other of DX12/GL (eframe reuses its event loop).
WGPU_BACKEND still overrides everything, and nothing else is tried then.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>