refactor(api): migrate controllers to Stream API with Base64 validation

PdfValidationController:
- ValidateFromFile: IFormFile.OpenReadStream() direct usage (no byte[] copy)
- ValidateFromBase64: try-catch Convert.FromBase64String → BadRequestException
- ValidatePdfAFromFile: IFormFile.OpenReadStream() direct usage
- ValidatePdfAFromBase64: try-catch Convert.FromBase64String → BadRequestException

PdfAttachmentController:
- CheckAttachmentsFromBase64: try-catch Convert.FromBase64String → BadRequestException

SwissQrCodeController:
- ExtractFromBase64: try-catch Convert.FromBase64String → BadRequestException

All controllers: Add using DocumentOperator.Domain.Common.Exceptions for BadRequestException

DocumentOperator.API/Controllers/SwissQrCodeController.cs

@@ -1,5 +1,6 @@
 using DocumentOperator.Application.Common.DTOs;
 using DocumentOperator.Application.SwissQrCode.Queries;
+using DocumentOperator.Domain.Common.Exceptions;
 using MediatR;
 using Microsoft.AspNetCore.Mvc;
 
@@ -17,7 +18,7 @@ public class SwissQrCodeController(IMediator Mediator) : ControllerBase
     /// Extracts Swiss QR Code from the last page of a PDF document (multipart/form-data)
     /// </summary>
     /// <param name="file">PDF file containing Swiss QR Code</param>
-    /// <param name="raw"></param>
+    /// <param name="raw">If true, returns raw QR text lines instead of parsed Bill object</param>
     /// <param name="cancellationToken">Cancellation token</param>
     /// <returns>Swiss QR Code data (IBAN, amount, creditor, debtor, reference, etc.)</returns>
     /// <response code="200">Swiss QR Code extracted successfully</response>
@@ -43,15 +44,13 @@ public class SwissQrCodeController(IMediator Mediator) : ControllerBase
                 Status = StatusCodes.Status400BadRequest
             });
 
-        // Convert IFormFile to byte array
-        using var memoryStream = new MemoryStream();
-        await file.CopyToAsync(memoryStream, cancellationToken);
-        byte[] pdfBytes = memoryStream.ToArray();
+        // Use IFormFile stream directly (no intermediate byte[] conversion)
+        using var pdfStream = file.OpenReadStream();
 
         // Direct pass-through to MediatR
         var query = new ExtractSwissQrCodeQuery 
         { 
-            PdfBytes = pdfBytes
+            PdfStream = pdfStream
         };
         var result = await Mediator.Send(query, cancellationToken);
 
@@ -61,8 +60,8 @@ public class SwissQrCodeController(IMediator Mediator) : ControllerBase
     /// <summary>
     /// Extracts Swiss QR Code from the last page of a PDF document (Base64 JSON)
     /// </summary>
-    /// <param name="query">References array + PDF as Base64 string</param>
-    /// <param name="raw"></param>
+    /// <param name="request">Request containing Base64-encoded PDF</param>
+    /// <param name="raw">If true, returns raw QR text lines instead of parsed Bill object</param>
     /// <param name="cancellationToken">Cancellation token</param>
     /// <returns>Swiss QR Code data (IBAN, amount, creditor, debtor, reference, etc.)</returns>
     /// <response code="200">Swiss QR Code extracted successfully</response>
@@ -76,13 +75,39 @@ public class SwissQrCodeController(IMediator Mediator) : ControllerBase
     [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status404NotFound)]
     [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
     public async Task<IActionResult> ExtractFromBase64(
-        [FromBody] ExtractSwissQrCodeQuery query,
+        [FromBody] ExtractSwissQrCodeBase64Request request,
         [FromQuery] bool raw = false,
         CancellationToken cancellationToken = default)
     {
+        // Convert Base64 to stream (wrap in try-catch to throw BadRequestException)
+        byte[] pdfBytes;
+        try
+        {
+            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
+        }
+        
+        using var pdfStream = new MemoryStream(pdfBytes);
+        
         // Direct pass-through to MediatR
+        var query = new ExtractSwissQrCodeQuery { PdfStream = pdfStream };
         var result = await Mediator.Send(query, cancellationToken);
 
         return Ok(raw ? result.RawLines : result.Bill);
     }
 }
+
+/// <summary>
+/// Request DTO for Base64-encoded Swiss QR Code extraction
+/// </summary>
+public record ExtractSwissQrCodeBase64Request
+{
+    /// <summary>
+    /// PDF document encoded as Base64 string
+    /// </summary>
+    /// <example>JVBERi0xLjQKJeLjz9MKMSAwIG9iago8PC9UeXBlL0NhdGFsb2c...</example>
+    public required string Base64Pdf { get; init; }
+}