test: reuse prebuilt docker e2e image

scripts/lib/docker-e2e-image.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+
+DOCKER_E2E_LIB_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ROOT_DIR="${ROOT_DIR:-$(cd "$DOCKER_E2E_LIB_DIR/../.." && pwd)}"
+
+source "$DOCKER_E2E_LIB_DIR/docker-e2e-logs.sh"
+
+docker_e2e_resolve_image() {
+  local default_image="$1"
+  shift
+
+  local env_name
+  for env_name in "$@"; do
+    local value="${!env_name:-}"
+    if [ -n "$value" ]; then
+      printf '%s\n' "$value"
+      return 0
+    fi
+  done
+
+  if [ -n "${OPENCLAW_DOCKER_E2E_IMAGE:-}" ]; then
+    printf '%s\n' "$OPENCLAW_DOCKER_E2E_IMAGE"
+    return 0
+  fi
+
+  printf '%s\n' "$default_image"
+}
+
+docker_e2e_build_or_reuse() {
+  local image_name="$1"
+  local label="$2"
+  local dockerfile="${3:-$ROOT_DIR/scripts/e2e/Dockerfile}"
+  local context="${4:-$ROOT_DIR}"
+  local target="${5:-}"
+  local skip_build="${6:-0}"
+
+  if [ "${OPENCLAW_SKIP_DOCKER_BUILD:-0}" = "1" ] || [ "$skip_build" = "1" ]; then
+    echo "Reusing Docker image: $image_name"
+    if ! docker image inspect "$image_name" >/dev/null 2>&1; then
+      echo "Docker image not found: $image_name" >&2
+      echo "Build it first or unset OPENCLAW_SKIP_DOCKER_BUILD." >&2
+      return 1
+    fi
+    return 0
+  fi
+
+  echo "Building Docker image: $image_name"
+  local build_cmd=(docker build)
+  if [ -n "$target" ]; then
+    build_cmd+=(--target "$target")
+  fi
+  build_cmd+=(-t "$image_name" -f "$dockerfile" "$context")
+  run_logged "$label-build" "${build_cmd[@]}"
+}