Use runtime base to break gateway build cycle

Dockerfile.runtime-base

@@ -0,0 +1,20 @@
+ARG BASE_IMAGE=mirror.gcr.io/library/debian:bookworm-slim
+FROM ${BASE_IMAGE}
+ARG SINGBOX_VERSION=1.12.13
+
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends ca-certificates curl iptables ipset iproute2 nodejs dumb-init \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN set -eux; \
+    arch="$(dpkg --print-architecture)"; \
+    case "$arch" in \
+    amd64) sb_arch="amd64" ;; \
+    arm64) sb_arch="arm64" ;; \
+    *) echo "Unsupported architecture: $arch" >&2; exit 1 ;; \
+    esac; \
+    curl -fsSL "https://github.com/SagerNet/sing-box/releases/download/v${SINGBOX_VERSION}/sing-box-${SINGBOX_VERSION}-linux-${sb_arch}.tar.gz" -o /tmp/sing-box.tgz; \
+    tar -xzf /tmp/sing-box.tgz -C /tmp; \
+    mv "/tmp/sing-box-${SINGBOX_VERSION}-linux-${sb_arch}/sing-box" /usr/local/bin/sing-box; \
+    chmod +x /usr/local/bin/sing-box; \
+    rm -rf /tmp/sing-box*