renderer_generated_frame_for_queue pushed a raw void* QVariant into the
display queue, but on_paint only unwraps OakSharedBufferPtr; the unwrap
failed and the widget painted blank. Paused display worked because
set_display_image wraps with oak_make_shared_frame. Wrap the queued
frames the same way. Also adds env-gated OAK_DEBUG_PLAYBACK
diagnostics.
Mike-Solar
6f931e720a
