Introduce Passkey support

(Missing Feature, Investigate , Priority: High, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Security
Summary: Add Passkey support for logging into Querki
It's pretty clear that this is the way the world is moving, and it's probably an improvement security-wise.
This probably has to come after we've updated to latest-and-greatest infrastructure, to be able to use recent libraries for it.
We'll probably have to support passwords indefinitely, but should eventually move to passkeys being the encouraged default.