Hey, thank you for reporting all of these! Currently there's no way to backup saves, in the next version I'll make a downloadable version available since some recurring issues seem to be due to the browser version.
I'm trying to reproduce the poison bug, maybe I accidentally fixed in my current version but I'll keep an eye for that. Antidote bug is fixed for the next version, thank you again for pointing it out, and the status icons seem to be an issue with the browser version too.
Luckily everything should be way more stable in the future non-browser version!