Thank you very much for your feedback!
I really could have written and run a server to sync and let the application run in a browser, but I deliberately gave up on that idea. Now the application is not dependent on anything and if I disappear somewhere it will remain functional. With servers, the ability to use the application will depend on whether I keep the server alive.
Plus, I would have to take responsibility for the privacy of your data, which is a serious and complex topic that I don't want to handle poorly.
It seems to me that the future of solving this problem lies in the area of decentralization. I am watching closely the development of peer to peer technology, but there is no elegant solution yet, developments in this direction are underway. Let's wait for the future :)
If there is anything else that could improve your experience with this application, I would be happy to hear and improve it.