Yuvomi

Changed

• Documentation only, no change to the application. docs/SPEC.md now records three calendar behaviours it did not carry: that choosing a view persists it while drilling into one does not (v2.51.0), how the view switcher and the calendar body relate as tablist and panel, and that the agenda shows today even when today is empty (both v2.51.1). The first of these is the reason the matching bug stayed invisible for a release: the specification described the intention, the code did more, and nobody reading the spec would have found a contradiction.