fix(quest): stabilize desktop and Steam layer presentation
Keep Quest SDR scenes and the black backdrop off the Android Vulkan swapchain regardless of session order or HDR preferences. Only report the first frame after client content is submitted.
Add backdrop lifecycle and first-frame regression coverage. Record the user's successful Quest 3 Test 2 result.
Co-authored-by: xXJsonDeruloXx <danielhimebauch@gmail.com>
