message: Update starting ref seq number in system events
diff: @@ -61,11 +61,11 @@ export function register(
  clientId: null,
  documentId: message.id,
  operation: {
  - clientSequenceNumber: -1,
  + clientSequenceNumber: 0,
  contents: clientId,
  encrypted: false,
  encryptedContents: null,
  - referenceSequenceNumber: -1,
  + referenceSequenceNumber: 0,
  type: api.ClientJoin,
  },
  timestamp: Date.now(),
  