Introduced multiple interfaces and DTOs to support a wide range of
PDF-related operations, including attachment handling, conversion,
validation, annotation, stamping, and metadata extraction.
Key changes:
- Added `DocumentServiceClientOptions` for HTTP client config.
- Introduced `IPdfAttachmentClient` for attachment operations.
- Added `IPdfConversionClient` for PDF/A conversion (marked obsolete).
- Added `IPdfOperationsClient` for merge, annotate, and stamp ops.
- Introduced `IPdfValidationClient` for PDF and PDF/A validation.
- Added `ISwissQrCodeClient` for Swiss QR Code extraction.
- Added `IZugferdClient` for ZUGFeRD detection and extraction.
- Created request DTOs for Base64-encoded operations.
- Added enums for annotation, stamp, and validation configurations.
These changes provide a flexible and extensible foundation for
interacting with PDF documents, supporting both multipart and
Base64-encoded inputs, and ensuring type safety with enums and records.
Introduced a new `DocumentService.Client` project targeting `net462`, `net480`, and `net8.0`. The project includes metadata for NuGet packaging, such as `PackageId`, `Authors`, and `Company`, and references `Microsoft.Extensions.DependencyInjection` and `Microsoft.Extensions.Logging`.
Updated `DocumentService.sln` to include the new project, its build configurations, and solution folder associations.
Added `icon.png` as the NuGet package icon and included it in the project file.
