Stem Slicer v0.1.0

feat: initial release v0.1.0 — pipeline de separacao de stems completo

C++17 standalone app com JUCE 7 + ONNX Runtime.
Pipeline STFT->inferencia->ISTFT com SNR 141 dB round-trip.
UI dark theme com drag-drop, barra de progresso e threading.
Modelo 4stems.onnx via Git LFS (Spleeter TF->ONNX).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>