activation of passkeys triggers unhandled server error

### Steps To Reproduce

Hello! I’m in the progress of trying out bitwarden as my new password management solution.

I use the unified image of bitwarden (docker).

So far the basic functionality works fine.

However, I run into a trouble when I want to enable any kind of passkey functionality for accessing Bitwarden itself. It doesn't matter whether I want to add a passkey as a second factor or if I want to enable the "Logon with passkey" function. In both cases the error looks the same.

In the case of "log on with passkey":
1) When I am logged on into the self-hosted bitwarden system via Chrome browser (I tried both Ubuntu as well Windows 11), I click on “turn on” for the feature.
2) I am being prompted to enter my master-password again.
3) Bitwarden triggers my browser to display a pop-up which asks me if I want to create a passkey for logon for the service (bitwarden).
4) It shows “Passkey successfully generated” and asks me for a name.
5) After entry of the name and clicking “turn on” again, it throws an “An unhandled server error has occurred.”

This is a screenshot of the error happening:

I tried two different kinds of passkeys: One with software + biometrics (Windows Hello), the other with hardware (Yubikey). In both cases, the error looks the same.

For troubleshooting, I then also tried to create an account with bitwarden online in the cloud (not self-hosted). I configured everything exactly the same there. There I could without any problems create and use both kinds of passkeys. So it has to be some problem with the unified image. I looked in the logs of the console of the container, but there wasn't anything interesting.

### Expected Result

passkey is created for further use

### Actual Result

error-message "An unhandled server error has occurred."

### Screenshots or Videos


### Additional Context

_No response_

### Githash Version

4a7db112-dirty

### Environment Details

Bitwarden 2025.5.0

### Database Image

SQLITE

### Issue-Link

https://github.com/bitwarden/server/issues/2480

### Issue Tracking Info

- [x] I understand that work is tracked outside of Github. A PR will be linked to this issue should one be opened to address it, but Bitwarden doesn't use fields like "assigned", "milestone", or "project" to track progress.