/** 表单选填项常为 null，PUT 时去掉以免后端对 null 调 trim */
export function omitNullFields<T extends Record<string, unknown>>(input: T): Partial<T> {
  const out: Partial<T> = {};
  for (const [key, value] of Object.entries(input)) {
    if (value === null || value === undefined) continue;
    (out as Record<string, unknown>)[key] = value;
  }
  return out;
}