ci: generate package list during compose via finalize.d

Avoid mounting the built image with buildah (ran out of disk); the
finalize.d hook records the rpm list next to the treefile and release.sh
consumes it directly.

build.sh

@@ -198,4 +198,11 @@ fi
   "${MANIFEST}" \
   "${OCI_ARCHIVE}"
 
+# The finalize.d hook records the installed package list next to the treefile.
+manifest_dir="$(dirname "${MANIFEST}")"
+if [[ -f "${manifest_dir}/packages-current.txt" ]]; then
+  cp "${manifest_dir}/packages-current.txt" "${BUILD_DIR}/packages-current.txt"
+  echo "Package list: ${BUILD_DIR}/packages-current.txt"
+fi
+
 echo "Built: ${OCI_ARCHIVE}"