Feat: display last used time of WebAuthn credentials

[bjoern-m]

Description

The details of a credential now also include the time when they were last used.

Implementation

DB changes:

• A new Fied LastUsedAt added to the WebauthnCredentials table

API changes:

• GET /webauthn/credentials will now return a list of credentials including last_used_at when present.
• When finalising a create credential request, LastUsedAt will be initialised with the current timestamp.
• When finalising a get credential request, LastUsedAt will be updated to the current timestamp.

Frontend SDK:

• DTO updated

Elements:

• The profile element will display the new date when expanding a passkey accordion tab (or a dash when unavailable).