refactor: Remove User model from Prisma schema to streamline database structure and improve maintainability

prisma/schema.prisma

@@ -7,18 +7,6 @@ datasource db {
   url      = env("DATABASE_URL")
 }
 
-model User {
-  id         Int      @id @default(autoincrement())
-  username   String   @unique
-  phone      String?
-  email      String?
-  password   String?
-  kakao_id   String?
-  avatar     String?
-  created_at DateTime @default(now())
-  updated_at DateTime @updatedAt
-}
-
 model MS_SUITABLE {
   id                                        Int      @id @default(autoincrement())
   product_name                              String   @db.VarChar(200)