Tasks: Support ESTIMATED-DURATION
In order to be able to take into account the time to spend / spent on a task, I would like to be able to edit their duration without having to specify a start date or end date.
Duration is indeed part of the CalDAV specification https://datatracker.ietf.org/doc/html/rfc4791 (as well as iCalendar's https://www.rfc-editor.org/rfc/rfc8607.html, see also https://www.grokkingandroid.com/recurrence-rule-and-duration-formats/ for how to write the duration format), but Evolution does not support it as far as I know.