Add Swiss QR Code extraction feature

Introduced DTOs for request and response to handle Swiss QR Code extraction from PDF documents. Implemented `ExtractSwissQrCodeHandler` to process the extraction using `ISwissQrCodeProcessor`. Added validation for the query with `ExtractSwissQrCodeValidator`. Developed unit tests to ensure correct behavior for successful and failure scenarios.

DocumentOperator.Application/Features/Documents/ExtractSwissQrCode/ExtractSwissQrCodeQuery.cs

@@ -0,0 +1,26 @@
+using DocumentOperator.Domain.Models.ValueObjects;
+using DocumentOperator.Domain.ValueObjects;
+using MediatR;
+
+namespace DocumentOperator.Application.Features.Documents.ExtractSwissQrCode;
+
+/// <summary>
+/// Query to extract Swiss QR Code data from a PDF document.
+/// Returns references (passed through) and parsed QR code data.
+/// </summary>
+/// <param name="References">Array of reference strings to pass through in the response</param>
+/// <param name="PdfContent">PDF document content as Base64 string</param>
+public record ExtractSwissQrCodeQuery(
+    IReadOnlyList<string> References,
+    Base64String PdfContent
+) : IRequest<ExtractSwissQrCodeResult>;
+
+/// <summary>
+/// Result containing passed-through references and extracted Swiss QR Code data
+/// </summary>
+/// <param name="References">Reference strings passed through from request</param>
+/// <param name="QrCodeData">Parsed Swiss QR Code data from the last page of the PDF</param>
+public record ExtractSwissQrCodeResult(
+    IReadOnlyList<string> References,
+    SwissQrCodeData QrCodeData
+);