Better reports and export system

Unfortunately, it is not possible to export more than three months of data, which limits the ability to perform long-term analyses.

It would also be useful to be able to customize the names of the weekly PDF reports. If this is too complicated, they should be given a more generic name with the date written backwards to allow us to sort the reports chronologically, for example:

2026-01-26 instead of 26 january 2026