add auth to backend and frontend

services/user.go

@@ -16,6 +16,20 @@ func NewUserService(db *sql.DB) *UserService {
 	return &UserService{db: db}
 }
 
+func (s *UserService) GetUserByID(id int) (*models.User, error) {
+	var user models.User
+	err := s.db.QueryRow(
+		`SELECT id, email, created_at FROM users WHERE id = $1`, id,
+	).Scan(&user.ID, &user.Email, &user.CreatedAt)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return &user, nil
+
+}
+
 func (s *UserService) CreateUser(email string, password string) (*models.User, error) {
 	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)