M2(Vulkan): capture hook via GPA interception + vkCmdCopyImageToBuffer read-back

New vk_hook.cpp inline-hooks the vulkan-1.dll vkGetInstanceProcAddr export and
hands back our wrappers for vkCreateInstance / vkCreateDevice / vkGetDeviceProcAddr
/ vkCreateSwapchainKHR / vkQueuePresentKHR, so a volk-using (loader-bypass) app
resolves our hooks. On present it reads the swap-chain image back with
vkCmdCopyImageToBuffer into a host-visible buffer (same read-back model as
D3D10/D3D9/OpenGL), swizzles BGRA->RGBA, and uploads it into the shared
keyed-mutex texture on a hook-owned D3D11 device. The read-back submit re-chains
the present's wait semaphores (consume the originals, signal our own that the
real present waits on) so capture orders after rendering without double-waiting.

Wired into the video subsystem with a lazy retry (vulkan-1.dll loads late). Hook
links the official Vulkan-Headers (headers only, VK_NO_PROTOTYPES) via the
include dir so the x86 sub-build builds too.

Because Vulkan caches its present pointer at init, late injection can't hook it:
mock_game_test launches the mock **suspended**, injects, resumes, and under
COOP_MOCK_VK_EARLY the mock loads Vulkan and waits so the hook arms first -- then
decodes frames through the hook like the other backends. 15/15 ctest (x64 +
x86); skips cleanly without a Vulkan driver.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tools/mock_game/main.cpp

@@ -96,6 +96,15 @@ int main(int argc, char** argv)
 		return 1;
 	}
 
+	// Test hook (early-load): Vulkan caches its present pointer at init, so the capture hook must
+	// be in place before vkCreateInstance. Under COOP_MOCK_VK_EARLY the mock loads vulkan-1.dll
+	// now and waits, giving an already-injected hook time to hook vkGetInstanceProcAddr first.
+	if (backend_name == "vk" && GetEnvironmentVariableW(L"COOP_MOCK_VK_EARLY", nullptr, 0) != 0)
+	{
+		LoadLibraryW(L"vulkan-1.dll");
+		Sleep(1500);
+	}
+
 	auto backend = coop::mock::RenderBackend::create(backend_name);
 	if (!backend || !backend->init(hwnd, kW, kH))
 	{