/**
 * 深度合并对象，保留未修改的字段
 */
export function deepMerge(target, source) {
  const result = { ...target };
  
  for (const key in source) {
    if (source[key] && typeof source[key] === 'object' && !Array.isArray(source[key])) {
      result[key] = deepMerge(target[key] || {}, source[key]);
    } else {
      result[key] = source[key];
    }
  }
  
  return result;
}