fix(ci): trim docker e2e heartbeat latency

scripts/lib/docker-build.sh

@@ -76,7 +76,7 @@ docker_build_timeout_required() {
 docker_build_heartbeat_seconds() {
   local configured="${OPENCLAW_DOCKER_BUILD_HEARTBEAT_SECONDS:-30}"
   if [[ "$configured" =~ ^[0-9]+$ ]] && [ "$configured" -ge 1 ]; then
-    echo "$configured"
+    echo "$((10#$configured))"
     return
   fi
   echo 30

scripts/lib/docker-e2e-logs.sh

@@ -35,19 +35,29 @@ run_logged_print_heartbeat() {
   local label="$1"
   local interval_seconds="$2"
   shift 2
+  if ! [[ "$interval_seconds" =~ ^[0-9]+$ ]] || [ "$interval_seconds" -lt 1 ]; then
+    interval_seconds="30"
+  else
+    interval_seconds="$((10#$interval_seconds))"
+  fi
   local log_file
   log_file="$(docker_e2e_run_log "$label")"
   "$@" >"$log_file" 2>&1 &
   local command_pid=$!
-  local started_at
-  started_at="$(date +%s)"
+  local started_at="$SECONDS"
+  local next_heartbeat=$interval_seconds
   local status=0
   while kill -0 "$command_pid" 2>/dev/null; do
-    sleep "$interval_seconds"
-    if kill -0 "$command_pid" 2>/dev/null; then
-      local now
-      now="$(date +%s)"
-      echo "still running $label ($((now - started_at))s elapsed)"
+    /bin/sleep 1
+    local elapsed_seconds=$((SECONDS - started_at))
+    if [ "$elapsed_seconds" -ge "$next_heartbeat" ] && kill -0 "$command_pid" 2>/dev/null; then
+      local log_bytes="0"
+      if [ -f "$log_file" ]; then
+        log_bytes="$(wc -c <"$log_file" 2>/dev/null || echo 0)"
+        log_bytes="${log_bytes//[[:space:]]/}"
+      fi
+      echo "still running $label (${elapsed_seconds}s elapsed, ${log_bytes} log bytes captured)"
+      next_heartbeat=$((elapsed_seconds + interval_seconds))
     fi
   done
   set +e