Add NVDEC headers and libnvcuvid stub for decord build

Dockerfile.gpu

@@ -24,6 +24,13 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     && ln -sf /usr/bin/python3.11 /usr/bin/python3 \
     && ln -sf /usr/bin/python3 /usr/bin/python
 
+# Download Video Codec SDK headers for NVDEC/NVCUVID
+RUN git clone https://github.com/FFmpeg/nv-codec-headers.git /tmp/nv-codec-headers && \
+    cd /tmp/nv-codec-headers && make install && rm -rf /tmp/nv-codec-headers
+
+# Create stub for libnvcuvid (real library comes from driver at runtime)
+RUN echo 'void* __nvcuvid_stub__;' | gcc -shared -x c - -o /usr/local/cuda/lib64/libnvcuvid.so
+
 # Build decord with CUDA support
 RUN git clone --recursive https://github.com/dmlc/decord /tmp/decord && \
     cd /tmp/decord && \