Adds a "Repeat" select (None / Daily / Weekly / Monthly / Yearly) that
reads/writes the existing Event.recurrence RRULE. CalDAV-imported rules
with extra parts (e.g. FREQ=WEEKLY;BYDAY=MO,WE,FR) surface as a disabled
"Custom" option with the raw rule shown read-only — visible but
preserved unless the user explicitly picks a preset to replace it.
EventUpdatePayload.recurrence is now string | null so we can clear via
PATCH; backend service already treats null as "clear" (recurrence is in
the nullable set in update_event).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
bvandeusen
36cd08c236