For when there's nothing to present to. Instead of a surface and swapchain,
it renders into images of its own through the VulkanPresentation interface
libretro uses, picking the graphics queue without a surface. Acquiring and
presenting signal and wait on the frame's semaphores with empty submits.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
VulkanGraphicsContext::InitSurface() threw away VulkanContext::InitSurface()'s
VkResult and carried on, so a failed surface init surfaced as
_dbg_assert_(GetAvailablePresentModes().size() > 0) in the VKContext
constructor rather than as a graphics error with the usual backend fallback.
The vkCreate*SurfaceKHR failure path in ReinitSurface() didn't log anything
either, so the assert was the only trace of it.
Now ReinitSurface() logs and sets init_error_ for all three ways it can bail
(surface creation, ChooseQueue, present mode enumeration), InitSurface()
checks the result, and MainThreadFunc() passes the message back out instead of
writing it to a local it then drops - Windows/main.cpp was reporting
"Failed to initialize main thread function." to the user.
Also deletes the Application on that failure path, which was leaked.
