[task] late alram (modal)

### ISSUE
- Group: `client`
-Type: `feature`
-Detail: this is nightmare

### TODO
1. [ ] 숫자 입력 칸(분) 구현
2. [ ] 확인 버튼 클릭시 본인을 제외한 해당 방에 있는 사람들에게 modal

### Estimated time
>Pick one

### `3h`

No files or tests are named. Start by locating the client-side room and modal entry points, then implement the minute input and confirmation flow described in the TODO; done means the modal reaches other people in the room but not the person who confirmed.

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