autoAcceptPeering means 'don't accept peering initiated by others', not
'don't initiate peering ourselves'. Two checks were incorrectly blocking
outgoing peering when auto-accept was off:
1. ensurePeered() refused to auto-initiate — reverted. When a local user
sends a DM, the server should initiate peering. The remote's
peer/accept decides whether to accept or queue.
2. queueOutboxEvent() refused to create placeholders — reverted. The
outbox needs placeholders to queue entries. Without them, DM relay
silently fails.