fix(quality): energy-aware reference trim before Demucs cleaning

perf(stopgap): trim reference to 10s before Demucs cleaning to bound CPU time

Revert "perf: run HT-Demucs reference cleaning on GPU (ZeroGPU CUDA EP)"

perf: run HT-Demucs reference cleaning on GPU (ZeroGPU CUDA EP)

fix: serialize prepare_conditionals->generate to stop cross-user voice leak

Pin demucs-onnx to 0.3.3 (Python 3.10 compatible)

Faithful-cloning defaults + sliders + optional background-audio removal (demucs-onnx)

Voice Clone Bench: Chatterbox Multilingual zero-shot cloning prototype

initial commit