steps to reproduce:

1 - Open a pad with a lot of content (~3-5mb worth of drawings)
2 - Try to rapidly draw many small changes
3 - Reload page to see what backend actually saved

You should see some changes not applied

This is probably happening because some more recent changes are applied before we got time to process some older ones, leading to the changes being ignored due to canvas versioning

We should instead make sure we process all the updates in the right order and making sure we skip none