Add a load more behaviour

[Fohlen]

Currently all the content is displayed at once. This notably impacts performance before for first input (as shown in the lighthouse report.pdf). The items should only be rendered once scrolling begins. Also try out whether or not a dedicated "load more" button is better for user experience on mobile.

[Fohlen]

We can listen to the scroll event like described in this article. However we do not need to do "infinite" scroll. Two months is sufficient, and since it is not a lot of data, it can be loaded all at once (this has the additional benefit of being a great offline app).