- 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