ci: bake cached toolchain into Podman agent and fix nested Buildah [CI]

ci/release-node-images.sh

@@ -32,6 +32,8 @@ netrc="$work/netrc"
 buildah_home="/home/justme/woodpecker/buildah-home/node-images"
 mkdir -p "$buildah_home"
 export HOME="$buildah_home"
+source "$root/ci/buildah-env.sh"
+moshiro_setup_buildah "$buildah_home"
 mkdir -p "$work"
 chmod 700 "$work"
 printf 'machine %s login justme password %s\n' "$gitea_host" "$GITEA_TOKEN" > "$netrc"