Use runtime base to break gateway build cycle

scripts/build-runtime-base.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+BASE_IMAGE="${BASE_IMAGE:-mirror.gcr.io/library/debian:bookworm-slim}"
+RUNTIME_BASE_IMAGE="${RUNTIME_BASE_IMAGE:-vpn-proxy-runtime-base:bookworm-slim}"
+SINGBOX_VERSION="${SINGBOX_VERSION:-1.12.13}"
+
+echo "Building runtime base: ${RUNTIME_BASE_IMAGE}"
+echo "Source base image: ${BASE_IMAGE}"
+
+docker build \
+  --build-arg BASE_IMAGE="${BASE_IMAGE}" \
+  --build-arg SINGBOX_VERSION="${SINGBOX_VERSION}" \
+  -f Dockerfile.runtime-base \
+  -t "${RUNTIME_BASE_IMAGE}" \
+  .