docs: log iterations 14-16 (full backend migration, middleware fix)

fix: replace dict State with flat primitive States to fix Gradio API schema TypeError

fix: remove np.ndarray type hints causing Gradio API schema 500 crash; store ref as list in State

feat: benchmark simulates frontend enrollment — mic input + cloned voice output

fix: pin torchaudio==2.5.1 + /health_hf via middleware + handoff docs (Iteration 9-10)

docs: mark iteration 9 as PASS in build error log

fix: add /health_hf via Starlette middleware patched into create_app

fix: use demo.server.config.app to access Gradio FastAPI app

fix: use prevent_thread_lock=True to get demo.server.app for /health_hf

fix: inject /health_hf via daemon thread polling demo.server

fix: inject /health_hf via gradio.routes.App.create_app patch

fix: add uvicorn.run() to block process after gr.mount_gradio_app()

feat: add /health_hf endpoint via gr.mount_gradio_app + FastAPI

fix: revert gradio to 5.x — 4.44.1 has Jinja unhashable dict + share=True errors

fix: remove torch CUDA pin conflicting with ZeroGPU, pin gradio==4.44.1