[task] 로그인 (page)

### ISSUE
- Group: `client`
-Type: `feature`
-Detail: login page

### TODO
1. [ ] 유효성 검사
2. [ ] 로그인 실패 한 경우(없는 정보) 인 경우 "정보를 다시 입력해주세요" 라는 문구 나타나기
3. [ ] 로그인 성공하면 홈화면으로 이동

### Estimated time
>Pick one

### `1.5h`

Start at the client login page entry point and inspect how its form and navigation are organized. Implement the listed validation, failed-login message, and successful redirect behavior; the work is done when invalid input is handled, missing credentials show the requested message, and successful login reaches the home screen.

Written by the indexing model from the issue text.