[task] 홈화면 제작(page)(비로그인)

### ISSUE
- Group: `client`
-Type: `feature`
-Detail: 홈화면(비로그인 작성시) 로고중심에 배경 css animation으로 간단한 화면 제작

### TODO
1. [x] css 기반 animation

### Estimated time
>Pick one

### `1.5h`

Start by locating the client-side entry point for the unauthenticated home screen and review its existing styles. No file or test is named in the issue. Done means a simple logo-centered home screen with a CSS-animated background is available for users who are not logged in.

Written by the indexing model from the issue text.