fix(service): run inbound deletes and depleted-client purges on the serial traffic writer (#6912)

Inbound and traffic writes are serialised on one goroutine because the traffic
poll locks inbounds then client_traffics while an admin mutation does the
reverse, which Postgres aborts as a deadlock (40P01). Deleting an inbound and
purging depleted clients still opened their own transactions, so they could
deadlock the poll, and a delete committing between a concurrent edit's read
and its Save let GORM's Save fall back to CREATE and resurrect the inbound.
Both now go through runSerializedTx like every other inbound write.

internal/web/service/inbound.go

@@ -1651,7 +1651,7 @@ func (s *InboundService) delInbound(id int) (bool, func(), error) {
 		logger.Debug("DelInbound: inbound not found, id:", id)
 	}
 
-	if err := db.Transaction(func(tx *gorm.DB) error {
+	if err := runSerializedTx(func(tx *gorm.DB) error {
 		if err := s.clientService.DetachInbound(tx, id); err != nil {
 			return err
 		}