add backup to webdav

[Fearless743]

i want backup data to my webdav service

[DennisBauer]

@Fearless743 this will require adding the internet permission to the app, but I was already thinking about doing some kind of online backup mechanism as it makes syncing data between devices that much simpler. And this will definitely be an opt in and optional feature

[825i]

Why not just backup to a folder and .md files locally which the user can use another app like Syncthing or Obsidian to sync? No need for internet permission.

[DennisBauer]

@825i backing up locally to use another sync app is already part of the other feature request #44.