Refactor: Rename DocumentOperator to DocumentService

Updated project and solution files to rename and restructure
`DocumentOperator` to `DocumentService`. Modified project
references in `DocumentService.API.csproj`, `DocumentService.Application.csproj`,
and `DocumentService.Infrastructure.csproj` to reflect the new
naming convention. Updated `DocumentService.sln` to remove
old project references, add new ones, and adjust configuration
and nested project mappings accordingly. This change aligns
the project structure with the new naming convention.

DocumentService.Application/SwissQrCode/Queries/ExtractSwissQrCodeQuery.cs

@@ -0,0 +1,44 @@
+using AutoMapper;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.Common.Interfaces;
+using MediatR;
+
+namespace DocumentService.Application.SwissQrCode.Queries;
+
+/// <summary>
+/// Query for extracting Swiss QR Code from PDF (Stream-based)
+/// </summary>
+public record ExtractSwissQrCodeQuery : IRequest<SwissQrCodeExtractionResult>
+{
+    /// <summary>
+    /// PDF as stream (caller is responsible for disposal)
+    /// </summary>
+    public required Stream PdfStream { get; init; }
+}
+
+/// <summary>
+/// Handler for ExtractSwissQrCodeQuery
+/// Orchestrates Swiss QR Code extraction using ISwissQrCodeProcessor and AutoMapper
+/// </summary>
+public class ExtractSwissQrCodeQueryHandler(ISwissQrCodeProcessor qrCodeProcessor, IMapper mapper) 
+    : IRequestHandler<ExtractSwissQrCodeQuery, SwissQrCodeExtractionResult>
+{
+    /// <summary>
+    /// Extracts and parses Swiss QR Code from the PDF (default: scans all pages starting with last)
+    /// Returns both parsed Bill DTO and raw QR text lines
+    /// </summary>
+    public async Task<SwissQrCodeExtractionResult> Handle(ExtractSwissQrCodeQuery request, CancellationToken cancellationToken)
+    {
+        // Extract: returns (Bill, RawLines) - pass stream directly
+        var (bill, rawLines) = await qrCodeProcessor.ExtractSwissQrCodeAsync(request.PdfStream, pageNumbers: null, cancellationToken);
+
+        // Map Codecrete Bill to DTO using AutoMapper
+        var billDto = mapper.Map<SwissQrBillDto>(bill);
+
+        // Return references (passed through) + Bill DTO + raw lines
+        return new SwissQrCodeExtractionResult(
+            Bill: billDto,
+            RawLines: rawLines
+        );
+    }
+}

DocumentService.Application/SwissQrCode/Queries/ExtractSwissQrCodeQueryValidator.cs

@@ -0,0 +1,19 @@
+using DocumentService.Application.SwissQrCode.Queries;
+using FluentValidation;
+
+namespace DocumentService.Application.SwissQrCode.Queries;
+
+/// <summary>
+/// Validates ExtractSwissQrCodeQuery before handler execution.
+/// Ensures PdfStream is not null.
+/// </summary>
+public sealed class ExtractSwissQrCodeQueryValidator : AbstractValidator<ExtractSwissQrCodeQuery>
+{
+    public ExtractSwissQrCodeQueryValidator()
+    {
+        // Rule: PdfStream must be provided
+        RuleFor(x => x.PdfStream)
+            .NotNull()
+            .WithMessage("PdfStream is required");
+    }
+}