refactor(application): migrate all queries to Stream-based API

- Replace byte[] and Base64String with required Stream PdfStream
- Simplify validators: remove XOR/Base64 validation, only check NotNull
- Affected queries: ValidatePdfQuery, ValidatePdfAQuery, CheckPdfAttachmentsQuery, ExtractSwissQrCodeQuery
- Memory efficiency: direct stream usage, no intermediate byte[] copies

DocumentOperator.Application/CheckPdfAttachments/Queries/CheckPdfAttachmentsQuery.cs

@@ -6,19 +6,14 @@ using MediatR;
 namespace DocumentOperator.Application.CheckPdfAttachments.Queries;
 
 /// <summary>
-/// Query for checking PDF attachments (supports both byte array and Base64 input)
+/// Query for checking PDF attachments (Stream-based)
 /// </summary>
 public record CheckPdfAttachmentsQuery : IRequest<AttachmentCheckResult>
 {
     /// <summary>
-    /// PDF as byte array (direct upload via multipart/form-data)
+    /// PDF as stream (caller is responsible for disposal)
     /// </summary>
-    public byte[]? PdfBytes { get; init; }
-
-    /// <summary>
-    /// PDF as Base64 string (for API clients using application/json)
-    /// </summary>
-    public string? Base64Pdf { get; init; }
+    public required Stream PdfStream { get; init; }
 }
 
 /// <summary>
@@ -33,14 +28,8 @@ public class CheckPdfAttachmentsQueryHandler(IPdfProcessor PdfProcessor, IMapper
     /// </summary>
     public async Task<AttachmentCheckResult> Handle(CheckPdfAttachmentsQuery request, CancellationToken cancellationToken)
     {
-        // Use byte[] if available, otherwise convert Base64
-        byte[] pdfBytes = request.PdfBytes ?? Convert.FromBase64String(request.Base64Pdf!);
-
-        // Convert to stream for IPdfProcessor
-        using var pdfStream = new MemoryStream(pdfBytes);
-
-        // Call DevExpress service (exceptions propagate naturally)
-        var attachmentInfo = await PdfProcessor.CheckAttachmentsAsync(pdfStream);
+        // Call DevExpress service directly with stream (exceptions propagate naturally)
+        var attachmentInfo = await PdfProcessor.CheckAttachmentsAsync(request.PdfStream);
 
         // Map DTO to response DTO using AutoMapper
         return Mapper.Map<AttachmentCheckResult>(attachmentInfo);