GLFW auto-iconifies an exclusive-fullscreen window on focus loss; for one
frame the window size reads 0x0 while the swapchain is still created, so
GameWindow.OnRender's PrepareFrame guard let a zero-area RenderFrameInput
through. The retail path tolerated it silently; the render-pack controller
correctly rejects a zero activation extent, which surfaced the latent frame
as an unhandled ArgumentOutOfRangeException during the owner's VM6/VM3 gate.
RenderFrameOrchestrator.Render now returns RenderFrameOutcome.ZeroArea
before BeginFrame when either dimension is <= 0 (no GPU frame, phase,
measurement, diagnostics or recovery runs) and GameWindow skips
NoteFrameClosed for it. Test: ZeroAreaViewport_SkipsTheFrameBeforeAnyGpuWork.
Verify: App hermetic lane 6,059/0 (Release).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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