Document measured runtime and the soundfile WAV-write delta

Size ZeroGPU duration from measured 1.89 s/step + 3 s fixed

Write WAV via soundfile (torchaudio 2.10 delegates save to torchcodec)

Tidy checkpoint step parsing

Fix Gradio 6 API: theme/css to launch(), drop show_download_button

OmniVAE T2AV demo: vendored reference pipeline + ZeroGPU Gradio app

initial commit