[x] If the user is already logged in and tries to reach these routes, they should be redirected to the Main page.
[x] Upon successful login, the user is redirected to the Main page.
[x] Client-side validation is implemented. (email and password strength - minimum 8 symbols, at least one letter, one digit, one special character, Unicode passwords must be supported)
пока ошибки через console.error(error), потом добавим вывод на страницу