feat: add support for anonymous NextAuth session

[SecondThundeR]

Currently, there are no way to play without Shikimori account

There are at least two ways I want to get around this:

• Create stateless games, which are available for certain time, e.g. 1 day, to share with someone or review results later (Easier to implement, but maybe not so user-friendly)
• Create anonymous session for keeping track of games played by user and connect them later on, when user will login to Shikimori account

Last idea is more suitable and more interesting, but challenging to implement