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/SwissQrCodeExtractionResult.cs

@@ -0,0 +1,116 @@
+namespace DocumentOperator.Application.Common.DTOs;
+
+/// <summary>
+/// Response containing extracted Swiss QR Code data and passed-through references.
+/// </summary>
+/// <param name="References">Reference strings passed through from the request</param>
+/// <param name="QrCodeData">Parsed Swiss QR Code data from the last page of the PDF</param>
+/// <example>
+/// {
+///   "references": ["REF-001", "REF-002"],
+///   "qrCodeData": {
+///     "qrType": "SPC",
+///     "version": "0200",
+///     "codingType": "1",
+///     "iban": "CH4431999123000889012",
+///     "creditor": {
+///       "addressType": "S",
+///       "name": "Robert Schneider AG",
+///       "street": "Rue du Lac",
+///       "buildingNumber": "1268",
+///       "postalCode": "2501",
+///       "city": "Biel",
+///       "country": "CH"
+///     },
+///     "amount": 1949.75,
+///     "currency": "CHF",
+///     "referenceType": "QRR",
+///     "reference": "210000000003139471430009017"
+///   }
+/// }
+/// </example>
+public record SwissQrCodeExtractionResult(
+    IReadOnlyList<string> References,
+    SwissQrCodeDataDto QrCodeData
+);
+
+/// <summary>
+/// Swiss QR Code data according to Swiss QR Bill Standard 2.0.
+/// Contains all fields defined in the Swiss Payment Standards.
+/// </summary>
+public record SwissQrCodeDataDto(
+    /// <summary>QR type - always "SPC" for Swiss Payment Code</summary>
+    string QrType,
+
+    /// <summary>Version of the Swiss QR Code standard (e.g., "0200" for version 2.0)</summary>
+    string Version,
+
+    /// <summary>Character set code (always "1" for UTF-8)</summary>
+    string CodingType,
+
+    /// <summary>IBAN of the creditor (payee)</summary>
+    string Iban,
+
+    /// <summary>Creditor (payee) information</summary>
+    AddressDataDto Creditor,
+
+    /// <summary>Ultimate creditor information (optional)</summary>
+    AddressDataDto? UltimateCreditor,
+
+    /// <summary>Payment amount (null if not specified)</summary>
+    decimal? Amount,
+
+    /// <summary>Currency code (CHF or EUR)</summary>
+    string Currency,
+
+    /// <summary>Ultimate debtor (payer) information (optional)</summary>
+    AddressDataDto? UltimateDebtor,
+
+    /// <summary>Reference type: "QRR" (QR Reference), "SCOR" (Creditor Reference ISO 11649), or "NON" (No Reference)</summary>
+    string ReferenceType,
+
+    /// <summary>Payment reference (format depends on ReferenceType)</summary>
+    string? Reference,
+
+    /// <summary>Unstructured message (max 140 characters)</summary>
+    string? UnstructuredMessage,
+
+    /// <summary>Bill information (structured data for automated processing)</summary>
+    string? BillInformation,
+
+    /// <summary>Alternative procedure parameters (up to 2 entries)</summary>
+    IReadOnlyList<string>? AlternativeProcedureParameters
+);
+
+/// <summary>
+/// Address data in Swiss QR Code (creditor or debtor).
+/// Can be either structured (S) or combined (K) format.
+/// </summary>
+public record AddressDataDto(
+    /// <summary>Address type: "S" for structured, "K" for combined</summary>
+    string AddressType,
+
+    /// <summary>Name of person or company</summary>
+    string Name,
+
+    /// <summary>Street name (structured address only)</summary>
+    string? Street,
+
+    /// <summary>Building number (structured address only)</summary>
+    string? BuildingNumber,
+
+    /// <summary>Address line 1 (combined address only)</summary>
+    string? AddressLine1,
+
+    /// <summary>Address line 2 (combined address only)</summary>
+    string? AddressLine2,
+
+    /// <summary>Postal code</summary>
+    string PostalCode,
+
+    /// <summary>City/town name</summary>
+    string City,
+
+    /// <summary>Two-letter country code (ISO 3166-1 alpha-2)</summary>
+    string Country
+);