refactor: Restructure Application layer with vertical slices and AutoMapper

Vertical slice architecture:

  - Move Features/Documents/{UseCase}/ to {UseCase}/Queries/

  - Query + Handler in SAME file (co-located)

  - Validator in separate file (single responsibility)

New structure:

  - ValidatePdf/Queries/ValidatePdfQuery.cs (Query + Handler)

  - ValidatePdf/Queries/ValidatePdfQueryValidator.cs

  - SwissQrCode/Queries/ExtractSwissQrCodeQuery.cs (Query + Handler)

  - SwissQrCode/Queries/ExtractSwissQrCodeQueryValidator.cs

AutoMapper integration:

  - Add Common/Mapping/MappingProfile.cs

  - Map PdfMetadata -> PdfValidationResult (domain -> DTO)

  - Map SwissQrCodeData -> SwissQrCodeExtractionResult (domain -> DTO)

  - Controllers now thin: pass request to MediatR, AutoMapper handles mapping

DTO improvements:

  - Rename: ValidatePdfResponse -> PdfValidationResult (business-friendly)

  - Rename: ExtractSwissQrCodeResponse -> SwissQrCodeExtractionResult

  - Support BOTH byte[] and Base64Pdf string (XOR validation)

  - Use modern C# 12 collection expressions

Code quality:

  - Use PascalCase for primary constructor parameters

  - Fix LoggingBehavior logging format

Deleted old structure:

  - Features/Documents/ValidatePdf/ (old horizontal structure)

  - Features/Documents/ExtractSwissQrCode/ (old horizontal structure)

  - Common/DTOs/{Request|Response} (replaced with {Result})

Result: Vertical slices, AutoMapper v16.2.0, thin controllers

DocumentOperator.Application/Common/DTOs/ExtractSwissQrCodeRequest.cs

@@ -1,18 +0,0 @@
-namespace DocumentOperator.Application.Common.DTOs;
-
-/// <summary>
-/// Request to extract Swiss QR Code from a PDF document.
-/// The QR code must be located on the last page of the document.
-/// </summary>
-/// <param name="References">Array of reference strings to pass through in the response</param>
-/// <param name="Base64Pdf">PDF document encoded as Base64 string</param>
-/// <example>
-/// {
-///   "references": ["REF-001", "REF-002"],
-///   "base64Pdf": "JVBERi0xLjQK..."
-/// }
-/// </example>
-public record ExtractSwissQrCodeRequest(
-    IReadOnlyList<string> References,
-    string Base64Pdf
-);

DocumentOperator.Application/Common/DTOs/PdfValidationResult.cs

@@ -4,12 +4,12 @@ namespace DocumentOperator.Application.Common.DTOs;
 /// Response mit PDF-Metadaten
 /// </summary>
 /// <param name="PageCount">Anzahl der Seiten</param>
-/// <param name="FileSizeBytes">Dateigröße in Bytes</param>
-/// <param name="FileSizeMB">Dateigröße in MB (gerundet auf 2 Dezimalstellen)</param>
+/// <param name="FileSizeBytes">Dateigröße in Bytes</param>
+/// <param name="FileSizeMB">Dateigröße in MB (gerundet auf 2 Dezimalstellen)</param>
 /// <param name="PdfVersion">PDF-Version (z.B. "1.4")</param>
-/// <param name="HasAttachments">Hat das PDF Anhänge?</param>
-/// <param name="AttachmentCount">Anzahl der Anhänge</param>
-public record ValidatePdfResponse(
+/// <param name="HasAttachments">Hat das PDF Anhänge?</param>
+/// <param name="AttachmentCount">Anzahl der Anhänge</param>
+public record PdfValidationResult(
     int PageCount,
     long FileSizeBytes,
     double FileSizeMB,

DocumentOperator.Application/Common/DTOs/SwissQrCodeExtractionResult.cs

@@ -29,7 +29,7 @@ namespace DocumentOperator.Application.Common.DTOs;
 ///   }
 /// }
 /// </example>
-public record ExtractSwissQrCodeResponse(
+public record SwissQrCodeExtractionResult(
     IReadOnlyList<string> References,
     SwissQrCodeDataDto QrCodeData
 );

DocumentOperator.Application/Common/DTOs/ValidatePdfRequest.cs

@@ -1,7 +0,0 @@
-namespace DocumentOperator.Application.Common.DTOs;
-
-/// <summary>
-/// Request für PDF-Validierung
-/// </summary>
-/// <param name="Base64Pdf">Base64-encodiertes PDF-Dokument</param>
-public record ValidatePdfRequest(string Base64Pdf);