Phase 2: Present-hook video path (shared-texture mirror)

Add an injected IDXGISwapChain::Present / Present1 hook as a lower-latency,
border-free alternative to WGC. The hook copies the swapchain backbuffer into a
shared keyed-mutex texture (coop_video_<pid>); the host opens it by name and
samples it. New opt-in HookSubsys_Video (protocol v6 -> v7); the Video mirror
panel gains a WGC vs Hooked source toggle that installs/removes the subsystem.

Verified by present_hook_test (drives a real D3D11 swapchain end-to-end and reads
the rendered pixels back through the shared texture) and against Phantom Brave
(D3D9: hook installs cleanly and stays idle, WGC fallback). All 5 tests pass.

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

tests/CMakeLists.txt

@@ -58,3 +58,24 @@ target_link_libraries(audio_hook_test PRIVATE
 	mmdevapi)
 
 add_test(NAME audio_hook_test COMMAND audio_hook_test)
+
+# In-process self-test for the Present-hook video path. Reuses the shipping
+# present_hook.cpp and drives a real D3D11 swapchain in the same process, so it
+# exercises the IDXGISwapChain::Present inline hook, the shared keyed-mutex
+# texture, and the open-by-name / readback contract (the video analogue of
+# audio_hook_test). Skips on a machine without a D3D11 device.
+add_executable(present_hook_test
+	present_hook_test.cpp
+	${CMAKE_SOURCE_DIR}/hook/src/present_hook.cpp
+	${CMAKE_SOURCE_DIR}/hook/src/debug_log.cpp
+	${CMAKE_SOURCE_DIR}/hook/src/hook_registry.cpp)
+
+target_include_directories(present_hook_test PRIVATE ${CMAKE_SOURCE_DIR}/hook/src)
+
+target_link_libraries(present_hook_test PRIVATE
+	coop_common
+	safetyhook::safetyhook
+	d3d11
+	dxgi)
+
+add_test(NAME present_hook_test COMMAND present_hook_test)