- `GetReferenceTypes`-Endpunkt im `HistoryController` hinzugefügt, um Key-Value-Paare des `ReferenceType`-Enums im camelCase-Format bereitzustellen.
- `ConfigurationService` in Angular erweitert, um die `ReferenceType`-Werte vom neuen API-Endpunkt abzurufen und zu speichern.
- Added a new `GetAllAsync` method to HistoryController to retrieve envelope histories.
- Included query parameters for filtering by envelopeId, userReference, referenceType, status, and boolean flags for sender and receiver.
- Implemented validation of `referenceType` with `ReferenceType` enum, throwing an error for invalid values.