Customer: { id?: string; name?: string; birthYear?: string; gender?: Gender; email?: string; phoneNumber?: string; address?: Address; zipcode?: string; } 타입 선언
Optionalid?: string
Optionalname?: string
OptionalbirthYear?: string
Optionalgender?: Gender
Optionalemail?: string
OptionalphoneNumber?: string
Optionaladdress?: Address
Optionalzipcode?: string
고객 정보