e8ff4df05f
Adds AudioSyncOffsetMs (0..500ms, default 0) that delays the whole interleaved-stereo mix so audio lands on the video when it runs ahead — OBS's documented lip-sync fix. Positive-only: advancing audio needs a video-side delay and is out of the audio layer's scope. - Services/Audio/AudioSyncDelay.cs: pure delay line, flushed on Configure - AudioMixer: Func<int> syncOffsetMs seam + delay applied post-limiter - LayoutStore.Settings + MainViewModel.Audio/VM: load/save + binding - PreviewPane mic bar: SYNC slider + status dot (IntToSyncBrushConverter) - AudioSyncDelayTests: identity, negative/beyond-500 clamps, 10ms→960 samples Reference (external scan): https://obs-versions.com/blog/how-to-fix-audio-delay-on-obs (audio ahead => positive delay). Verified: build 0 warnings; 3/3 delay tests pass.