feat(auth): implement web login endpoint with JWT

internal/database/user_repository.go

@@ -176,3 +176,25 @@ func (r *UserRepository) UpdateSkinHash(ctx context.Context, userID int, skinHas
 
 	return nil
 }
+
+// GetUserByLogin находит пользователя по его имени или email.
+func (r *UserRepository) GetUserByLogin(ctx context.Context, login string) (*models.User, error) {
+	user := &models.User{}
+	var userUUID string
+
+	// Ищем по username ИЛИ по email
+	query := "SELECT id, uuid, username, email, password_hash, role, created_at, updated_at FROM users WHERE username = $1 OR email = $1"
+	err := r.DB.QueryRowContext(ctx, query, login).Scan(
+		&user.ID, &userUUID, &user.Username, &user.Email, &user.PasswordHash, &user.Role, &user.CreatedAt, &user.UpdatedAt,
+	)
+
+	if err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			return nil, ErrUserNotFound
+		}
+		return nil, err
+	}
+
+	user.UUID, _ = uuid.Parse(userUUID)
+	return user, nil
+}