remove lightning dep (not needed, breaks CPU torch index)

Dockerfile

@@ -77,7 +77,7 @@ RUN curl -fL --retry 3 --retry-delay 5 -o /app/models/vae-BF16.gguf \
 RUN pip3 install --no-cache-dir --extra-index-url https://download.pytorch.org/whl/cpu \
     "gradio[mcp]>=6.0.0,<7.0.0" requests torch safetensors \
     "transformers>=4.51.0,<4.58.0" peft>=0.18.0 \
-    loguru "torchaudio==2.4.0" "diffusers==0.30.3" lightning numpy tensorboard soundfile \
+    loguru "torchaudio==2.4.0" "diffusers==0.30.3" numpy tensorboard soundfile \
     einops vector_quantize_pytorch librosa mutagen demucs-infer \
     faster-whisper silero-vad