Introduced a new `WorkflowsClient` to orchestrate multi-step
operations, combining `IPdfValidationClient` and
`ISwissQrCodeClient`. Added methods to validate PDFs and extract
Swiss QR Codes in a single call, with overloads for byte arrays,
streams, and file paths. Registered `WorkflowsClient` as a scoped
service in `ServiceCollectionExtensions`.
Updated `PdfValidationResult` with an `IsValid` property to
simplify PDF validity checks. Added `IWorkflowsClient` interface
to define the contract for the new client, with detailed XML
documentation for its methods.