Data export: Improve timestamp format for easier parsing

The timestamp columns in the data exports could be improved for easier parsing and handling by adding

  • a timezone offset from UTC and/or the timezone at the end of the timestamp to ensure timestamps are read and understood correctly independent of the server / participant settings
  • replacing the current ((locale dependent) character %b with a zero-padded numeric %m to allow for easier parsing independent of research locale (2025-Mär-01 → 2025-03-01)

In short: Adhering to ISO 8601 for timestamps (Date and Time incl. seconds) with timezone offset from UTC would probably solve most problems. As an example August 11th 2025 at exactly 2pm in Germany would translate to

2025-08-11T14:00:00+0200
Edited by Max