moved Users from models to domain

backend/user/model.go

@@ -0,0 +1,14 @@
+package user
+
+import (
+	"time"
+)
+
+type User struct {
+	UserID       uint      `gorm:"primaryKey" json:"id"`
+	Username     string    `gorm:"unique" json:"name"`
+	PasswordHash string    `json:"password"`
+	Email        string    `gorm:"unique" json:"email"`
+	CreatedAt    time.Time `json:"created_at"`
+	UpdatedAt    time.Time `json:"updated_at"`
+}