fix(02): show owner name / Family in event popover footer

Backend:
- expand.ts: add ownerName: string | null to CalendarOccurrence
  interface and expandOccurrences() signature; thread it onto every
  emitted occurrence.
- events.ts: SELECT users.displayName as ownerName in the join; pass
  it to expandOccurrences().

Frontend:
- client.ts: add ownerName: string | null to CalendarOccurrence.
- EventDetailPopover.tsx: render isShared ? 'Family' :
  (ownerName ?? calendarName) in the footer instead of calendarName.

Tests:
- expand.test.ts: pass ownerName to all expandOccurrences() calls;
  assert ownerName is carried onto occurrences in the DST test.
- events.test.ts: add ownerName to mock rows; assert ownerName present
  on occurrences; add ownerName assertion to timed-recurring test.
- EventDetailPopover.test.tsx: add ownerName to fixtures; split
  "calendar name in footer" into three targeted tests covering
  personal-with-owner, shared→Family, and null-owner fallback.

apps/api/src/routes/events.ts

@@ -82,6 +82,7 @@ eventsRouter.get('/', zValidator('query', eventsQuerySchema), async (c) => {
         isShared: calendars.isShared,
         userId: users.id,
         userColor: users.color,
+        ownerName: users.displayName,
       })
       .from(calendarEvents)
       .innerJoin(calendars, eq(calendarEvents.calendarId, calendars.id))
@@ -126,6 +127,7 @@ eventsRouter.get('/', zValidator('query', eventsQuerySchema), async (c) => {
         row.calendarId,
         row.calendarName ?? '',
         row.userId,
+        row.ownerName ?? null,
         color,
         row.isShared,
       )