feat: 新增 models.go 定义基础模型和枚举类型，并创建 auth_service.go 文件。

internal/service/auth_service.go

@@ -171,6 +171,7 @@ func (s *AuthService) Login(input LoginInput) (*models.User, *TokenPair, error)
 		return nil, nil, err
 	}
 
+	user.HasPassword = true
 	return user, tokens, nil
 }
 
@@ -231,7 +232,12 @@ func (s *AuthService) ValidateEmail(email string) bool {
 
 // GetUserByID retrieves a user by ID
 func (s *AuthService) GetUserByID(id uint) (*models.User, error) {
-	return s.userRepo.GetByID(id)
+	user, err := s.userRepo.GetByID(id)
+	if err != nil {
+		return nil, err
+	}
+	user.HasPassword = user.PasswordHash != ""
+	return user, nil
 }
 
 // generateTokenPair generates access and refresh tokens
@@ -286,9 +292,11 @@ func (s *AuthService) UpdatePassword(userID uint, oldPassword, newPassword strin
 		return err
 	}
 
-	// Verify old password
-	if err := bcrypt.CompareHashAndPassword([]byte(user.PasswordHash), []byte(oldPassword)); err != nil {
-		return ErrInvalidCredentials
+	// Verify old password only if user has a password set
+	if user.PasswordHash != "" {
+		if err := bcrypt.CompareHashAndPassword([]byte(user.PasswordHash), []byte(oldPassword)); err != nil {
+			return ErrInvalidCredentials
+		}
 	}
 
 	// Validate new password