[FEATURE REQUEST] add multi users support (groups sharing with permissions management and geolocation history)

At the moment,

I created five different folders, one for each family member, on the webdav server with different user/pass each, configured all different sync settings on each iPhone and I have to copy the files from first uploading folder to the others "share" each others.

But it's frustrating, would no be better to give as an option the possibility:

use an https python/nodejs service connected to a PostgreSQL to serve the images ?
the service could check user access info and present only all the cards it has access rights.
the service could compare current phone location to look in another table for the card used last time in the same from same or other users and present it at the top, so don't waste time on the queue at desk to search for it.

And that would give tons of room for further improvements in my opinion.

Thanks

No files, tests, or entry points are identified in the issue. Start by reviewing the existing iPhone sync and WebDAV flows, then define the scope for shared groups, permissions, image serving, and location history before identifying implementation and testing points.