The agenda part filtered calendars through the search settings and always
collapsed after four rows. It now has its own selection: an exclusion set
(`clockWidgetCalendarPartExcludedCalendars`, empty = all) that is added to the
search settings' exclusions, because the picker only offers calendars those
settings leave enabled.
The row cap is `clockWidgetCalendarPartMaxRows` (1..8, default 4); the agenda
shows that many events and then a "+N more events" row if more are left, so
with the default five events now render as four rows plus "+1 more event"
instead of three plus "+2".
Both are configured in `ConfigureCalendarPart`, shown by the clock sheet while
the Events part is enabled: a slider, a Calendars row that expands into a
colour-tinted checkbox per calendar, and a button to Settings -> Search ->
Calendar (new `ROUTE_SEARCH_CALENDARS`) for calendars the search settings
disable. A missing calendar permission shows a banner with a Grant button.
New setting fields default to the previous behaviour, so no datastore
migration is needed.
Jonas Haugesen
c824b100b6