fix: download-tools 使用 gh-proxy 镜像地址解决构建时网络不通问题

pack/Dockerfile

@@ -535,8 +535,8 @@ RUN --mount=type=cache,target=/root/.cache \
     uv pip install --no-build-isolation --extra-index-url https://download.pytorch.org/whl/cpu/ --index-url https://mirrors.tuna.tsinghua.edu.cn/pypi/web/simple \
         ${WHEEL_PACKAGE}
 
-    # Download tools
-    gpustack download-tools
+    # Download tools (use gh-proxy mirror for China network)
+    gpustack download-tools --tools-download-base-url "https://gh-proxy.com/https://github.com"
     tree -hs "$(pip show gpustack | grep Location: | head -n 1 | cut -d" " -f 2)/gpustack/third_party"
 
     # Set up environment