Map macOS arm64 to aarch64 for the debian13 multiarch directory

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

debian13/build.sh

@@ -15,7 +15,11 @@ fi
 
 SOURCES_DIR="$SOURCES_DIR" "$FETCH_SCRIPT"
 
+# macOS reports arm64 where Linux (and Debian multiarch) call it aarch64.
+ARCH=$(uname -m)
+[ "$ARCH" = arm64 ] && ARCH=aarch64
+
 echo "Building image $IMAGE_NAME with podman (prefix $PREFIX) ..."
 exec podman build --build-context sources="$SOURCES_DIR" \
-    --build-arg PREFIX="$PREFIX" --build-arg MULTIARCH="$(uname -m)-linux-gnu" \
+    --build-arg PREFIX="$PREFIX" --build-arg MULTIARCH="$ARCH-linux-gnu" \
     --tag "$IMAGE_NAME" "$SCRIPT_DIR"