[Task] DB 스키마 적용

### ISSUE
- Group: `server`
- Type: `feature`
- Detail: fix DataBase schema structure

### TODO
1. [x] generate sequelize DB
2. [x] generate standard table
3. [x] associate with join table
4. [x] migrate sequelize DB

### Estimated time
### `0.5h`

### Labels
- Estimated time: `E: 0.5h`
- Group : `server`
- Sprint: `Sprint__NUMBER__1`
- Urgency: `Middle`

Start by reviewing the generated Sequelize DB, standard tables, join-table association, and migration referenced in the TODO. Confirm the database schema structure and migration behavior; all four checklist items are already marked complete.

Written by the indexing model from the issue text.