[Task](Advanced) Sign Up node mailer(코드 전송 및 확인) 요청

### TODO
1. [x] 코드 전송 클릭시 클라이언트에서 온 이메일 및 바디에 code라는 이름으로 전송

### Estimated time
>Pick one

### `1h`

The issue identifies an advanced signup mailer task for sending and confirming a code, with the client email and a body field named code sent when the user clicks the send-code control. Start by locating the signup mailer and code-verification entry points; done should cover both delivery and confirmation, but the issue names no files, tests, or acceptance criteria.

Written by the indexing model from the issue text.