Convert to multi-arch docker image.

build-base/build.sh

@@ -4,7 +4,12 @@ set -euo pipefail
 
 SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
 
-docker build \
+# Create buildx builder if it doesn't exist
+docker buildx create --name multiarch --use 2>/dev/null || docker buildx use multiarch
+
+# Build multi-platform image locally (store in builder cache)
+docker buildx build \
+  --platform linux/amd64,linux/arm64 \
   -t "gitea.jde.nz/public/dropshell-build-base:latest" \
   -f "${SCRIPT_DIR}/Dockerfile.dropshell-build-base" \
   ${SCRIPT_DIR}