- Add syncForMember(memberId) to SubscriptionSyncService: creates the
  member's own FY subscription row + syncs all currently-active dependents
  in one call. Uses same rate/discount/dedup logic as the batch generator.
- Wire member.activated EventBus listener in Subscriptions bootstrap so
  any newly-activated member (and their dependents) gets a subscription row
  immediately, without waiting for the next annual batch generation.
- Existing syncForDependent is unchanged; syncForMember delegates to it.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>