Don't allow new users to jump directly to level 1

[kbuzzard]

It would be better if we forced them to click on the big tutorial world and then they will see the brief overview of tactics and the game objective (which they can choose to read or ignore). Right now they might accidentally miss it.

[joneugster]

Right now, the introduction is always shown when selecting level 1.

Would be better to store in the local storage if the player read the introduction and use this.

[joneugster]

I'll close this as the current behaviour (always opening level 0 instead of 1) is acceptable in my opinion. And if not, this issue would belong to the lean4game repo instead