/export-questions should be treated differently

[omiras]

Acabado con issure #27

Ademas encontrado que si usuario va a la ruta /export-questions sin poner ?numberQuestions=[number], en este caso el servidor deja funcionar.
He areglado esta cosa con implemetacion de download-error.ejs para mandar una pantalla informativa a usuari como el puede descargar fichero con preguntas :

A normal user using a web browser should not be able to perform a GET request to /export-questions.

That said, at least we provide a clear and user-friendly error message. However, the user may not understand why they cannot access this endpoint. Additionally, only we, as developers, are aware of the existence of /export-questions.

With this in mind, we could consider the following options:

1. Set Default Values:
   If a user performs a GET request to /export-questions without a query string, we could set default values for numberQuestions. This way, the user would experience some "magic" functionality even if they don’t understand where the behavior originates.

2. Optimal Approach:
   If no numberQuestions parameter is provided to the endpoint, we could use res.redirect to send the user to /template-form.

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Acceptance Criteria

• If a user navigates directly to /export-questions, they should be redirected to /template-form.
• If a user navigates to /template-form, they should be able to download a file compatible with either the Kahoot or Blooket applications.