fix: resolve 4 pre-existing test failures in channelserver

- Guard nil listener/acceptConns in Server.Shutdown() to prevent panic
  in test servers that don't bind a network listener
- Remove redundant userBinaryPartsLock in TestHandleMsgMhfLoaddata that
  caused a deadlock with handleMsgMhfLoaddata's own lock acquisition
- Increase test save blob size from 200 to 150000 bytes to accommodate
  ZZ save pointer offsets (up to 146728)
- Initialize MHFEquipment.Sigils[].Effects slices in test data to
  prevent index-out-of-range panic in SerializeWarehouseEquipment
- Insert warehouse row before updating it (UPDATE on 0 rows is not an
  error, so the INSERT fallback never triggered)
- Use COALESCE for nullable kouryou_point column in kill counter test
- Fix duplicate-add test expectation (CSV helper correctly deduplicates)

server/channelserver/sys_channel_server.go

@@ -223,9 +223,13 @@ func (s *Server) Shutdown() {
 	s.isShuttingDown = true
 	s.Unlock()
 
-	_ = s.listener.Close()
+	if s.listener != nil {
+		_ = s.listener.Close()
+	}
 
-	close(s.acceptConns)
+	if s.acceptConns != nil {
+		close(s.acceptConns)
+	}
 }
 
 func (s *Server) acceptClients() {