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/PdfValidationController.cs

@@ -1,6 +1,7 @@
 using DocumentOperator.Application.Common.DTOs;
 using DocumentOperator.Application.ValidatePdf.Queries;
 using DocumentOperator.Application.ValidatePdfA.Queries;
+using DocumentOperator.Domain.Common.Exceptions;
 using MediatR;
 using Microsoft.AspNetCore.Mvc;
 
@@ -42,13 +43,11 @@ public class PdfValidationController(IMediator Mediator) : ControllerBase
             });
         }
 
-        // 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 ValidatePdfQuery { PdfBytes = pdfBytes };
+        var query = new ValidatePdfQuery { PdfStream = pdfStream };
         var result = await Mediator.Send(query, cancellationToken);
         
         return Ok(result);
@@ -57,7 +56,7 @@ public class PdfValidationController(IMediator Mediator) : ControllerBase
     /// <summary>
     /// Validates a PDF document and returns metadata (Base64 JSON)
     /// </summary>
-    /// <param name="query">PDF as Base64 string</param>
+    /// <param name="request">Request containing Base64-encoded PDF</param>
     /// <param name="cancellationToken">Cancellation token</param>
     /// <returns>PDF metadata (page count, file size, PDF version, attachments)</returns>
     /// <response code="200">PDF is valid, metadata returned</response>
@@ -69,10 +68,24 @@ public class PdfValidationController(IMediator Mediator) : ControllerBase
     [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
     [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
     public async Task<IActionResult> ValidateFromBase64(
-        [FromBody] ValidatePdfQuery query,
+        [FromBody] ValidatePdfBase64Request request,
         CancellationToken cancellationToken)
     {
+        // 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 ValidatePdfQuery { PdfStream = pdfStream };
         var result = await Mediator.Send(query, cancellationToken);
         
         return Ok(result);
@@ -106,13 +119,11 @@ public class PdfValidationController(IMediator Mediator) : ControllerBase
             });
         }
 
-        // 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 ValidatePdfAQuery { PdfBytes = pdfBytes };
+        var query = new ValidatePdfAQuery { PdfStream = pdfStream };
         var result = await Mediator.Send(query, cancellationToken);
         
         return Ok(result);
@@ -121,7 +132,7 @@ public class PdfValidationController(IMediator Mediator) : ControllerBase
     /// <summary>
     /// Validates a PDF/A document and checks conformance level (Base64 JSON)
     /// </summary>
-    /// <param name="query">PDF as Base64 string</param>
+    /// <param name="request">Request containing Base64-encoded PDF</param>
     /// <param name="cancellationToken">Cancellation token</param>
     /// <returns>PDF/A metadata (conformance level, errors, warnings)</returns>
     /// <response code="200">PDF/A validation completed, results returned</response>
@@ -133,12 +144,50 @@ public class PdfValidationController(IMediator Mediator) : ControllerBase
     [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
     [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
     public async Task<IActionResult> ValidatePdfAFromBase64(
-        [FromBody] ValidatePdfAQuery query,
+        [FromBody] ValidatePdfABase64Request request,
         CancellationToken cancellationToken)
     {
+        // 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 ValidatePdfAQuery { PdfStream = pdfStream };
         var result = await Mediator.Send(query, cancellationToken);
         
         return Ok(result);
     }
 }
+
+/// <summary>
+/// Request DTO for Base64-encoded PDF validation
+/// </summary>
+public record ValidatePdfBase64Request
+{
+    /// <summary>
+    /// PDF document encoded as Base64 string
+    /// </summary>
+    /// <example>JVBERi0xLjQKJeLjz9MKMSAwIG9iago8PC9UeXBlL0NhdGFsb2c...</example>
+    public string Base64Pdf { get; init; } = string.Empty;
+}
+
+/// <summary>
+/// Request DTO for Base64-encoded PDF/A validation
+/// </summary>
+public record ValidatePdfABase64Request
+{
+    /// <summary>
+    /// PDF document encoded as Base64 string
+    /// </summary>
+    /// <example>JVBERi0xLjQKJeLjz9MKMSAwIG9iago8PC9UeXBlL0NhdGFsb2c...</example>
+    public string Base64Pdf { get; init; } = string.Empty;
+}