Second slice of milestone 2 (write support):
- EventForm domain model + problems() validation (end-before-start,
no-calendar; blank titles and instant events stay legal)
- Full-screen EventEditScreen: title, all-day switch, M3 date/time pickers
(moving the start preserves the duration), calendar picker limited to
writable calendars, location, description. Save validates, requests the
WRITE upgrade contextually, and closes on success
- Calendar preselection: explicit pick > last-used (CalendarPrefs) > first
writable calendar
- insertEvent in the data source; EventWriteMapper (JVM-tested) normalises
all-day events to UTC midnights with exclusive DTEND, timed events to the
device zone
- CalendarFabColumn shared by month/week/day: persistent "+" FAB anchored on
the visible day, jump-to-today pill stacked above it
- Tests: EventForm validation, write-time mapping (incl. DST-safe epoch
check), repository createEvent delegation/error propagation
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Jean-Luc Makiola
c59a071b82