Fall back to wget in ensure_node when curl is unavailable

The self-hosted qa runner has neither curl nor wget guaranteed; ensure_node
previously assumed curl, breaking smoke-qa on that host.

scripts/ci/lib.sh

@@ -68,7 +68,14 @@ ensure_node() {
   if [[ ! -x "$install_dir/bin/node" ]]; then
     log "node not found on PATH; installing Node.js v$node_version"
     local tarball="node-v${node_version}-linux-x64"
-    curl -fsSL "https://nodejs.org/dist/v${node_version}/${tarball}.tar.xz" -o "/tmp/${tarball}.tar.xz"
+    local url="https://nodejs.org/dist/v${node_version}/${tarball}.tar.xz"
+    if command -v curl > /dev/null 2>&1; then
+      curl -fsSL "$url" -o "/tmp/${tarball}.tar.xz"
+    elif command -v wget > /dev/null 2>&1; then
+      wget -q "$url" -O "/tmp/${tarball}.tar.xz"
+    else
+      fail "neither curl nor wget found on PATH; cannot download Node.js"
+    fi
     mkdir -p "$install_dir"
     tar -xJf "/tmp/${tarball}.tar.xz" -C "$install_dir" --strip-components=1
     rm -f "/tmp/${tarball}.tar.xz"