Add VERSICHERUNG_FILTER="DAK" to config and apply it to all case
queries: list, detail, pending-icd, pending-coding, coding queue,
dashboard KPIs, all 5 report sheets, and excel sync export.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
.cast(int) uses Python's builtin int, which lacks SQLAlchemy's
_isnull attribute. Replace all occurrences with .cast(Integer).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>