add API solution

MareSynchronosAPI/DownloadFileDto.cs

@@ -0,0 +1,11 @@
+namespace MareSynchronos.API
+{
+    public record DownloadFileDto : ITransferFileDto
+    {
+        public bool FileExists { get; set; } = true;
+        public string Hash { get; set; } = string.Empty;
+        public long Size { get; set; } = 0;
+        public bool IsForbidden { get; set; } = false;
+        public string ForbiddenBy { get; set; } = string.Empty;
+    }
+}