Fix missing hipblas/MIOpen dev packages in builder stage

Install hipblas-dev and miopen-hip-dev, and set CMAKE_PREFIX_PATH=/opt/rocm
so cmake can locate the hipblasConfig.cmake and MIOpen config files.

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

Dockerfile

@@ -12,6 +12,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
         git cmake cmake-curses-gui \
         libopenblas-dev wget \
         python3-dev python3-pip \
+        hipblas-dev miopen-hip-dev \
     && rm -rf /var/lib/apt/lists/*
 
 # Build oneDNN as a static library (CPU fallback / conv ops)
@@ -41,6 +42,7 @@ RUN git clone --branch v4.0.0 --depth 1 \
     git apply /tmp/ct2_4.0.0_rocm.patch && \
     mkdir build && cd build && \
     cmake -DCMAKE_INSTALL_PREFIX=${CTRANSLATE2_ROOT} \
+          -DCMAKE_PREFIX_PATH=/opt/rocm \
           -DWITH_CUDA=ON \
           -DWITH_CUDNN=ON \
           -DWITH_MKL=OFF \