Remove AddAttachmentsRequest record from PdfAttachmentRequests

The `AddAttachmentsRequest` record has been removed. This record was previously used as a request DTO for adding attachments to a Base64-encoded PDF. It included a `Base64Pdf` property for the PDF document and an `Attachments` property for the list of attachments to embed.

The `ExtractPdfAttachmentsRequest` and `AttachmentRequestDto` records remain unchanged.

DocumentService.Client/Models/Requests/PdfAttachmentRequests.cs

@@ -24,23 +24,6 @@ public record ExtractPdfAttachmentsRequest
     public required string Base64Pdf { get; init; }
 }
 
-/// <summary>
-/// Request DTO for Base64-encoded PDF with attachments to add
-/// </summary>
-public record AddAttachmentsRequest
-{
-    /// <summary>
-    /// PDF document encoded as Base64 string
-    /// </summary>
-    /// <example>JVBERi0xLjQKJeLjz9MKMSAwIG9iago8PC9UeXBlL0NhdGFsb2c...</example>
-    public required string Base64Pdf { get; init; }
-
-    /// <summary>
-    /// List of attachments to embed
-    /// </summary>
-    public required List<AttachmentRequestDto> Attachments { get; init; }
-}
-
 /// <summary>
 /// DTO for attachment file in request
 /// </summary>