Updated `PdfSignOptionsDto` and `PdfSignatureCheckItemDto` to use `DocumentElementId` (long) instead of `UUID` (string). Modified `PdfDigitalSignatureService` to reflect this change, including updates to `SignatureReasonMetaRegex`, `BuildReasonWithMeta`, and `ParseReasonMeta`. Adjusted method signatures, return values, and property assignments to ensure consistent use of `DocumentElementId`. These changes align with a shift in the application's data model to use numeric identifiers for document elements.