CaseResponse.nachname was required (str) but the masking function sets
it to None for dak_mitarbeiter. This caused Pydantic validation errors
(500) making the case list empty for non-admin users.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The field was editable in the frontend but missing from the backend
CaseUpdate Pydantic schema, causing changes to be silently dropped.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>