feat: add --no-rollback flag to deploy script

When --no-rollback is set, the script keeps the new version on the
server even if health check fails, making it possible to inspect
startup logs via journalctl to diagnose the issue.

deploy/deploy.sh

 APP_NAME="iot-platform"
 LOCAL_JAR=""
 DO_BUILD=false
+NO_ROLLBACK=false
 
 # 颜色
 RED='\033[0;31m'
             DO_BUILD=true
             shift
             ;;
+        --no-rollback)
+            NO_ROLLBACK=true
+            shift
+            ;;
         --jar)
             LOCAL_JAR="$2"
             shift 2
             ;;
         --help|-h)
-            echo "用法: ./deploy.sh [--build] [--jar <path>]"
-            echo "  --build     本地执行 mvn clean package"
-            echo "  --jar       指定要部署的 jar 文件路径"
+            echo "用法: ./deploy.sh [--build] [--no-rollback] [--jar <path>]"
+            echo "  --build        本地执行 mvn clean package"
+            echo "  --no-rollback  健康检查失败时不自动回滚，保留新版本用于排查"
+            echo "  --jar          指定要部署的 jar 文件路径"
             exit 0
             ;;
         *)
     ssh "${SERVER_USER}@${SERVER_HOST}" "systemctl status ${APP_NAME} --no-pager"
     exit 0
 else
-    echo -e "${RED}[6/6] 健康检查失败! 执行回滚...${NC}"
+    echo -e "${RED}[6/6] 健康检查失败!${NC}"
+
+    if [ "$NO_ROLLBACK" = true ]; then
+        echo -e "${YELLOW}[no-rollback] 已启用不回滚模式，保留新版本用于排查${NC}"
+        echo -e "${YELLOW}排查命令:${NC}"
+        echo "  ssh ${SERVER_USER}@${SERVER_HOST} 'journalctl -u ${APP_NAME} -f'"
+        echo "  ssh ${SERVER_USER}@${SERVER_HOST} 'systemctl status ${APP_NAME}'"
+        exit 1
+    fi
 
-    # 回滚
-    echo -e "${YELLOW}[rollback] 停止服务...${NC}"
+    echo -e "${YELLOW}[rollback] 执行回滚...${NC}"
     ssh "${SERVER_USER}@${SERVER_HOST}" "systemctl stop ${APP_NAME} || true"
 
     if ssh "${SERVER_USER}@${SERVER_HOST}" "test -f ${REMOTE_DIR}/backup/${BACKUP_NAME}"; then