fix(02): populate hasRrule on every sync upsert so recurring masters are flagged

- Use ICAL.Event.isRecurring() (parity with expand.ts) to detect RRULE/RDATE
- Add hasRrule to .values() INSERT and .onDuplicateKeyUpdate() SET so the flag
  is set on first sync and self-heals on every subsequent re-sync
- Without this fix every event had has_rrule=0 (column default), causing the
  events route recurring-master pre-filter to return zero recurring occurrences
- Add sync.test.ts cases: hasRrule=true for timed+all-day recurring VEVENTs,
  hasRrule=false for non-recurring, and hasRrule in onDuplicateKeyUpdate.set

apps/api/tests/helpers/db.ts

@@ -57,3 +57,34 @@ DTEND;VALUE=DATE:20260616
 SUMMARY:Test All-Day Event
 END:VEVENT
 END:VCALENDAR`
+
+/**
+ * Sample VEVENT string — a timed recurring event (RRULE:FREQ=WEEKLY).
+ * Used to test that sync sets hasRrule=true for recurring events.
+ */
+export const SAMPLE_VEVENT_RECURRING_TIMED = `BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//FamilySync//Test//EN
+BEGIN:VEVENT
+UID:test-recurring-timed-001@familysync
+DTSTART:20240101T100000Z
+RRULE:FREQ=WEEKLY;BYDAY=MO
+SUMMARY:Weekly Monday Meeting
+END:VEVENT
+END:VCALENDAR`
+
+/**
+ * Sample VEVENT string — an all-day recurring event (RRULE:FREQ=YEARLY).
+ * Used to test that sync sets hasRrule=true for all-day recurring events,
+ * and that the events route returns occurrences even when dtstartUtc is NULL.
+ */
+export const SAMPLE_VEVENT_RECURRING_ALLDAY = `BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//FamilySync//Test//EN
+BEGIN:VEVENT
+UID:test-recurring-allday-001@familysync
+DTSTART;VALUE=DATE:20240615
+RRULE:FREQ=YEARLY
+SUMMARY:Annual Birthday
+END:VEVENT
+END:VCALENDAR`