Enhanced PDF signing with UUID and metadata handling:
- Added `UUID` and `OriginalDocumentSha256` to `PdfSignOptionsDto` and `PdfSignatureCheckItemDto`.
- Introduced `BusinessReason` to separate metadata from signature reasons.
- Updated `PdfDigitalSignatureService` to embed and parse metadata in signature reasons.
- Improved error handling to include metadata in validation results.
- Updated `PdfSignatureController` to handle `UUID` in signing requests.
Refactored PKCS#11 configuration:
- Replaced `LibraryPath` with `AssetsRootPath` for asset resolution.
- Added `ProxySocket` and `DefaultApplicationName` options.
- Clarified runtime behavior for asset resolution in `README.md`.
Updated documentation and examples to reflect these changes.
Introduced `Pkcs11Options` for configuring PKCS#11 signing workflows, including properties for library path, token selection, and signing metadata. Added `PdfSignOptionsDto` to represent signing options and `PdfSignatureCheckResultDto` with related DTOs for signature validation.
Defined `PdfSignatureCertificationLevel` enum for certification levels. Added `IPdfDigitalSignatureService` interface to support signing and validating PDF signatures. These changes enable robust and extensible handling of digital signatures.
