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/Common/DTOs/AttachmentCheckResult.cs

@@ -0,0 +1,43 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// DTO for attachment check result returned to API layer
+/// </summary>
+public record AttachmentCheckResult
+{
+    /// <summary>
+    /// Indicates whether the PDF contains any attachments
+    /// </summary>
+    public bool HasAttachments { get; init; }
+
+    /// <summary>
+    /// Total number of attachments in the PDF
+    /// </summary>
+    public int AttachmentCount { get; init; }
+
+    /// <summary>
+    /// List of attachment metadata (file details)
+    /// </summary>
+    public List<AttachmentDto> Attachments { get; init; } = new();
+}
+
+/// <summary>
+/// DTO for individual attachment metadata
+/// </summary>
+public record AttachmentDto
+{
+    /// <summary>
+    /// Attachment file name (e.g., "invoice.xml", "document.pdf")
+    /// </summary>
+    public string FileName { get; init; } = string.Empty;
+
+    /// <summary>
+    /// MIME type of the attachment (e.g., "text/xml", "application/pdf")
+    /// </summary>
+    public string MimeType { get; init; } = string.Empty;
+
+    /// <summary>
+    /// Attachment file size in bytes
+    /// </summary>
+    public long Size { get; init; }
+}

DocumentService.Application/Common/DTOs/AttachmentInfo.cs

@@ -0,0 +1,60 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// Represents complete attachment information for a PDF document.
+/// Immutable value object containing attachment presence flag, count, and detailed metadata.
+/// </summary>
+public sealed class AttachmentInfo
+{
+    /// <summary>
+    /// Gets a value indicating whether the PDF contains any attachments
+    /// </summary>
+    public bool HasAttachments { get; }
+
+    /// <summary>
+    /// Gets the total number of attachments in the PDF
+    /// </summary>
+    public int AttachmentCount { get; }
+
+    /// <summary>
+    /// Gets the collection of attachment metadata (file details)
+    /// </summary>
+    public IReadOnlyList<AttachmentMetadata> Attachments { get; }
+
+    /// <summary>
+    /// Initializes a new instance of the AttachmentInfo class.
+    /// </summary>
+    /// <param name="hasAttachments">Whether PDF has attachments</param>
+    /// <param name="attachmentCount">Total number of attachments</param>
+    /// <param name="attachments">List of attachment metadata (can be empty)</param>
+    public AttachmentInfo(bool hasAttachments, int attachmentCount, IReadOnlyList<AttachmentMetadata> attachments)
+    {
+        HasAttachments = hasAttachments;
+        AttachmentCount = attachmentCount;
+        Attachments = attachments ?? [];
+
+        // Defensive Programming: Ensure count matches list length
+        if (Attachments.Count != attachmentCount)
+        {
+            throw new ArgumentException(
+                $"Attachment count mismatch: expected {attachmentCount}, got {Attachments.Count}",
+                nameof(attachments));
+        }
+    }
+
+    /// <summary>
+    /// Creates an AttachmentInfo instance for a PDF with no attachments.
+    /// </summary>
+    public static AttachmentInfo Empty =>
+        new(
+            hasAttachments: false,
+            attachmentCount: 0,
+            attachments: []);
+
+    public override string ToString()
+    {
+        return HasAttachments
+            ? $"PDF has {AttachmentCount} attachment(s): {string.Join(", ", Attachments.Select(a => a.FileName))}"
+            : "PDF has no attachments";
+    }
+}

DocumentService.Application/Common/DTOs/AttachmentMetadata.cs

@@ -0,0 +1,44 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// Represents metadata of a single PDF attachment (embedded file).
+/// Immutable value object containing file information without the actual binary data.
+/// </summary>
+/// <remarks>
+/// Initializes a new instance of the AttachmentMetadata class.
+/// </remarks>
+/// <param name="fileName">Attachment file name</param>
+/// <param name="mimeType">MIME type (e.g., "text/xml")</param>
+/// <param name="sizeBytes">File size in bytes</param>
+public sealed class AttachmentMetadata(string fileName, string mimeType, long sizeBytes)
+{
+    /// <summary>
+    /// Gets the attachment file name (e.g., "invoice.xml", "document.pdf")
+    /// </summary>
+    public string FileName { get; } = fileName ?? string.Empty;
+
+    /// <summary>
+    /// Gets the MIME type of the attachment (e.g., "text/xml", "application/pdf")
+    /// </summary>
+    public string MimeType { get; } = mimeType ?? "application/octet-stream"; // Default MIME type if unknown
+
+    /// <summary>
+    /// Gets the attachment file size in bytes
+    /// </summary>
+    public long SizeBytes { get; } = sizeBytes;
+
+    /// <summary>
+    /// Gets the attachment file size in kilobytes (computed property)
+    /// </summary>
+    public double SizeKB => SizeBytes / 1024.0;
+
+    /// <summary>
+    /// Gets the attachment file size in megabytes (computed property)
+    /// </summary>
+    public double SizeMB => SizeBytes / 1024.0 / 1024.0;
+
+    public override string ToString()
+    {
+        return $"{FileName} ({MimeType}, {SizeKB:F2} KB)";
+    }
+}

DocumentService.Application/Common/DTOs/PdfAValidationResult.cs

@@ -0,0 +1,52 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// PDF/A validation result including conformance level and validation errors/warnings
+/// </summary>
+public record PdfAValidationResult
+{
+    /// <summary>
+    /// Whether the PDF is valid (no errors)
+    /// </summary>
+    public bool IsValid { get; init; }
+
+    /// <summary>
+    /// PDF version (e.g., "1.4", "1.7")
+    /// </summary>
+    public string PdfVersion { get; init; } = string.Empty;
+
+    /// <summary>
+    /// Number of pages in the PDF
+    /// </summary>
+    public int PageCount { get; init; }
+
+    /// <summary>
+    /// File size in bytes
+    /// </summary>
+    public long FileSize { get; init; }
+
+    /// <summary>
+    /// Whether the PDF is encrypted
+    /// </summary>
+    public bool Encrypted { get; init; }
+
+    /// <summary>
+    /// PDF/A version (e.g., "PDF/A-1b", "PDF/A-2a", "PDF/A-3u") or null if not PDF/A compliant
+    /// </summary>
+    public string? PdfAVersion { get; init; }
+
+    /// <summary>
+    /// Whether the PDF conforms to PDF/A standard
+    /// </summary>
+    public bool PdfACompliant { get; init; }
+
+    /// <summary>
+    /// Validation errors (e.g., "PDF/A documents cannot be encrypted")
+    /// </summary>
+    public IReadOnlyList<string> Errors { get; init; } = [];
+
+    /// <summary>
+    /// Validation warnings (e.g., "Manual verification recommended: All fonts must be embedded")
+    /// </summary>
+    public IReadOnlyList<string> Warnings { get; init; } = [];
+}

DocumentService.Application/Common/DTOs/PdfValidationResult.cs

@@ -0,0 +1,20 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// 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="PdfVersion">PDF-Version (z.B. "1.4")</param>
+/// <param name="HasAttachments">Hat das PDF Anhänge?</param>
+/// <param name="AttachmentCount">Anzahl der Anhänge</param>
+/// <param name="IsEncrypted">Ist das PDF passwortgeschützt/verschlüsselt?</param>
+public record PdfValidationResult(
+    int PageCount,
+    long FileSizeBytes,
+    double FileSizeMB,
+    string PdfVersion,
+    bool HasAttachments,
+    int AttachmentCount,
+    bool IsEncrypted);

DocumentService.Application/Common/DTOs/SwissQrBillDto.cs

@@ -0,0 +1,93 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// Swiss QR Bill data transfer object (mapped from Codecrete Bill)
+/// </summary>
+public record SwissQrBillDto
+{
+    /// <summary>QR Bill standard version (e.g., "V2_0")</summary>
+    public required string Version { get; init; }
+
+    /// <summary>Payment amount (null if not specified)</summary>
+    public decimal? Amount { get; init; }
+
+    /// <summary>Payment currency (CHF or EUR)</summary>
+    public required string Currency { get; init; }
+
+    /// <summary>Creditor's IBAN account number</summary>
+    public required string Account { get; init; }
+
+    /// <summary>Creditor address</summary>
+    public required AddressDto Creditor { get; init; }
+
+    /// <summary>Payment reference type: "QRR", "SCOR", or "NON"</summary>
+    public required string ReferenceType { get; init; }
+
+    /// <summary>Payment reference (format depends on ReferenceType)</summary>
+    public string? Reference { get; init; }
+
+    /// <summary>Debtor address (optional)</summary>
+    public AddressDto? Debtor { get; init; }
+
+    /// <summary>Additional unstructured message (max 140 chars)</summary>
+    public string? UnstructuredMessage { get; init; }
+
+    /// <summary>Additional structured bill information</summary>
+    public string? BillInformation { get; init; }
+
+    /// <summary>Alternative payment schemes (max 2)</summary>
+    public IReadOnlyList<AlternativeSchemeDto>? AlternativeSchemes { get; init; }
+}
+
+/// <summary>
+/// Address data transfer object (mapped from Codecrete Address)
+/// </summary>
+public record AddressDto
+{
+    /// <summary>Address type: "Structured" or "CombinedElements"</summary>
+    public required string Type { get; init; }
+
+    /// <summary>Name of person or company</summary>
+    public required string Name { get; init; }
+
+    /// <summary>Street name (structured address only)</summary>
+    public string? Street { get; init; }
+
+    /// <summary>House number (structured address only)</summary>
+    public string? HouseNo { get; init; }
+
+    /// <summary>
+    /// Address line 1 (combined address only).
+    /// OBSOLETE: Use structured address instead. Will be removed when Codecrete v4 is adopted.
+    /// </summary>
+    [Obsolete("Use structured address (Street + HouseNo) instead. This field will be removed when upgrading to Codecrete.SwissQRBill.Generator v4.x")]
+    public string? AddressLine1 { get; init; }
+
+    /// <summary>
+    /// Address line 2 (combined address only).
+    /// OBSOLETE: Use structured address instead. Will be removed when Codecrete v4 is adopted.
+    /// </summary>
+    [Obsolete("Use structured address (Street + HouseNo) instead. This field will be removed when upgrading to Codecrete.SwissQRBill.Generator v4.x")]
+    public string? AddressLine2 { get; init; }
+
+    /// <summary>Postal code</summary>
+    public required string PostalCode { get; init; }
+
+    /// <summary>Town/city name</summary>
+    public required string Town { get; init; }
+
+    /// <summary>Two-letter country code (ISO 3166-1 alpha-2)</summary>
+    public required string CountryCode { get; init; }
+}
+
+/// <summary>
+/// Alternative payment scheme (mapped from Codecrete AlternativeScheme)
+/// </summary>
+public record AlternativeSchemeDto
+{
+    /// <summary>Scheme name (e.g., "AV1", "AV2")</summary>
+    public required string Name { get; init; }
+
+    /// <summary>Scheme instruction/parameter</summary>
+    public required string Instruction { get; init; }
+}

DocumentService.Application/Common/DTOs/SwissQrCodeExtractionResult.cs

@@ -0,0 +1,37 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// Response containing extracted Swiss QR Code in dual format.
+/// </summary>
+/// <param name="Bill">Parsed Swiss QR Bill (structured format)</param>
+/// <param name="RawLines">Raw Swiss QR Code lines (original newline-separated format)</param>
+/// <example>
+/// {
+///   "bill": {
+///     "version": "V2_0",
+///     "amount": 630.20,
+///     "currency": "CHF",
+///     "account": "CH953000520280564701R",
+///     "creditor": {
+///       "type": "Structured",
+///       "name": "ALMAT AG",
+///       "town": "Tagelswangen"
+///     },
+///     "referenceType": "QRR",
+///     "reference": "000000000000000000252080824"
+///   },
+///   "rawLines": [
+///     "SPC",
+///     "0200",
+///     "1",
+///     "CH953000520280564701R",
+///     "S",
+///     "ALMAT AG",
+///     "..."
+///   ]
+/// }
+/// </example>
+public record SwissQrCodeExtractionResult(
+    SwissQrBillDto Bill,
+    IReadOnlyList<string> RawLines
+);

DocumentService.Application/Common/DTOs/ZugferdCheckResult.cs

@@ -0,0 +1,27 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// DTO for ZUGFeRD check result
+/// </summary>
+public record ZugferdCheckResult
+{
+    /// <summary>
+    /// Indicates whether the PDF contains ZUGFeRD XML attachment
+    /// </summary>
+    public bool HasZugferd { get; init; }
+
+    /// <summary>
+    /// ZUGFeRD XML file name (e.g., "factur-x.xml")
+    /// </summary>
+    public string? ZugferdFileName { get; init; }
+
+    /// <summary>
+    /// ZUGFeRD XML file size in bytes
+    /// </summary>
+    public long? ZugferdFileSize { get; init; }
+
+    /// <summary>
+    /// MIME type of the ZUGFeRD XML file
+    /// </summary>
+    public string? ZugferdMimeType { get; init; }
+}