added comments

backend/internal/model/auth.go

@@ -14,11 +14,13 @@ const (
 	RoleGuest Role = "guest"
 )
 
+// InvalidJWT Represents a JWT that has expired or is otherwise invalid.
 type InvalidJWT struct {
 	JWT        string `gorm:"primarykey"`
 	ValidUntil time.Time
 }
 
+// User represents a user with an ID, UUID, name, role, and password.
 type User struct {
 	ID       uint      `gorm:"primarykey" json:"-"`
 	UUID     uuid.UUID `gorm:"type:uuid" json:"uuid"`
@@ -27,6 +29,7 @@ type User struct {
 	Password []byte    `json:"-"`
 }
 
+// NewUser creates a new User struct with a generated UUID.
 func NewUser() User {
 	return User{
 		UUID: uuid.New(),