feat: package GPU libraries inside backend containers for unified base image (#7891)

* Initial plan

* Add GPU library packaging for isolated backend environments

- Create scripts/build/package-gpu-libs.sh for packaging CUDA, ROCm, SYCL, and Vulkan libraries
- Update llama-cpp, whisper, stablediffusion-ggml package.sh to include GPU libraries
- Update Dockerfile.python to package GPU libraries into Python backends
- Update libbackend.sh to set LD_LIBRARY_PATH for GPU library loading

Co-authored-by: mudler <2420543+mudler@users.noreply.github.com>

* Address code review feedback: fix variable consistency and quoting

Co-authored-by: mudler <2420543+mudler@users.noreply.github.com>

* Fix code review issues: improve glob handling and remove redundant variable

Co-authored-by: mudler <2420543+mudler@users.noreply.github.com>

* Simplify main Dockerfile and workflow to use unified base image

- Remove GPU-specific driver installation from Dockerfile (CUDA, ROCm, Vulkan, Intel)
- Simplify image.yml workflow to build single unified base image for linux/amd64 and linux/arm64
- GPU libraries are now packaged in individual backend containers

Co-authored-by: mudler <2420543+mudler@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: mudler <2420543+mudler@users.noreply.github.com>
Co-authored-by: Ettore Di Giacinto <mudler@users.noreply.github.com>

backend/python/common/libbackend.sh

@@ -465,6 +465,14 @@ function startBackend() {
     if [ "x${PORTABLE_PYTHON}" == "xtrue" ] || [ -x "$(_portable_python)" ]; then
         _makeVenvPortable --update-pyvenv-cfg
     fi
+
+    # Set up GPU library paths if a lib directory exists
+    # This allows backends to include their own GPU libraries (CUDA, ROCm, etc.)
+    if [ -d "${EDIR}/lib" ]; then
+        export LD_LIBRARY_PATH="${EDIR}/lib:${LD_LIBRARY_PATH:-}"
+        echo "Added ${EDIR}/lib to LD_LIBRARY_PATH for GPU libraries"
+    fi
+
     if [ ! -z "${BACKEND_FILE:-}" ]; then
         exec "${EDIR}/venv/bin/python" "${BACKEND_FILE}" "$@"
     elif [ -e "${MY_DIR}/server.py" ]; then