copy the next.config.js in order to get custom domains working (for alternative s3 providers) again

[justcallmelarry]

Background

The custom s3 domains have stopped working for me, as the domain never gets added to the runtime next config. Next complains about the url not being whitelisted for loading images (but not in a clear way…)

This seems to have been the case since https://github.com/spliit-app/spliit/pull/91 which removed files (among other fixes) in order to make the the Docker image smaller.

Fix

The easy fix is just adding back the next.config.js to the runtime environment, since this fix was already added in https://github.com/spliit-app/spliit/pull/71 in order to get the custom domains working in the first case.