better support of raw data transfer

Pilz.Net/Api/ApiClient.cs

@@ -55,7 +55,16 @@ public class ApiClient(string apiUrl) : IApiClient
         TResponse? result = null;
 
         if (res.IsSuccessStatusCode)
+        {
+            var mediaType = res.Content.Headers.ContentType?.MediaType;
+            if (!string.IsNullOrWhiteSpace(mediaType))
+            {
+                if (mediaType == "application/json")
                     result = serializer.Deserialize(await res.Content.ReadAsStringAsync(), typeof(TResponse)) as TResponse;
+                else if (typeof(TResponse).IsAssignableTo(typeof(ApiRawMessage)) && mediaType == "application/octet-stream")
+                    result = (TResponse)(object)new ApiRawMessage(await res.Content.ReadAsByteArrayAsync());
+            }
+        }
 
         return new(res, result);
     }

Pilz.Net/Api/ApiRawMessage.cs

@@ -0,0 +1,6 @@
+namespace Pilz.Net.Api;
+
+public class ApiRawMessage(byte[] data) : ApiMessage
+{
+    public byte[] Data { get; } = data;
+}

Pilz.Net/Api/ApiServer.cs

@@ -411,6 +411,7 @@ public class ApiServer : IApiServer
         else if (result.ResultContent is byte[] resultBytes)
         {
             Log.Info("Sending raw bytes response for " + context.Request.RawUrl);
+            context.Response.ContentType = "application/octet-stream";
             context.Response.OutputStream.Write(resultBytes, 0, resultBytes.Length);
             context.Response.OutputStream.Flush();
         }
@@ -455,6 +456,10 @@ public class ApiServer : IApiServer
         if (result.Message is null)
             return new(result, null);
 
+        // Return result with raw data
+        if (result.Message is ApiRawMessage dataMsg)
+            return new(result, dataMsg.Data);
+
         // Serializer
         Log.Debug("Serialize message");
         if (serializer.Serialize(result.Message) is not string resultStr)