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/tests/broker/expand.test.ts

@@ -46,6 +46,7 @@ describe('expandOccurrences', () => {
         1,          // calendarId
         'My Calendar', // calendarName
         1,          // ownerUserId
+        'Alice',    // ownerName
         '#4A90D9',  // color
         false,      // isShared
       )
@@ -58,6 +59,8 @@ describe('expandOccurrences', () => {
       // after DST: '...T10:00:00-04:00[America/New_York]'. Both include the IANA bracket.
       for (const occ of occurrences) {
         expect(occ.allDay).toBe(false)
+        // ownerName must be threaded through to every occurrence
+        expect(occ.ownerName).toBe('Alice')
         // start must be IANA-annotated: '2026-03-01T10:00:00-05:00[America/New_York]'
         expect(occ.start).toMatch(/T10:00:00/)
         // Must include IANA bracket — offset-only strings fail Temporal.ZonedDateTime.from()
@@ -96,6 +99,7 @@ describe('expandOccurrences', () => {
         1,
         'My Calendar',
         1,
+        null,       // ownerName
         '#4A90D9',
         false,
       )
@@ -127,6 +131,7 @@ describe('expandOccurrences', () => {
         1,
         'My Calendar',
         1,
+        null,       // ownerName
         '#4A90D9',
         false,
       )
@@ -156,6 +161,7 @@ describe('expandOccurrences', () => {
         1,
         'My Calendar',
         1,
+        null,       // ownerName
         '#4A90D9',
         false,
       )
@@ -196,6 +202,7 @@ describe('expandOccurrences', () => {
         1,
         'My Calendar',
         1,
+        null,       // ownerName
         '#4A90D9',
         false,
       )