Use GetBytes overload with offset and count parameters

Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>

Author: Copilot

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerResource.cs

@@ -396,8 +396,8 @@ public override async ValueTask<ReadResourceResult> ReadAsync(
  { 
  Uri = request.Params!.Uri, 
  MimeType = dc.MediaType, 
- Blob = MemoryMarshal.TryGetArray(dc.Base64Data, out ArraySegment<char> segment) && segment.Offset == 0 && segment.Count == segment.Array!.Length 
- ? System.Text.Encoding.UTF8.GetBytes(segment.Array) 
+ Blob = MemoryMarshal.TryGetArray(dc.Base64Data, out ArraySegment<char> segment)
+ ? System.Text.Encoding.UTF8.GetBytes(segment.Array!, segment.Offset, segment.Count) 
  : System.Text.Encoding.UTF8.GetBytes(dc.Base64Data.ToString()) 
  }],
  },
@@ -428,8 +428,8 @@ public override async ValueTask<ReadResourceResult> ReadAsync(
  {
  Uri = request.Params!.Uri,
  MimeType = dc.MediaType,
- Blob = MemoryMarshal.TryGetArray(dc.Base64Data, out ArraySegment<char> segment) && segment.Offset == 0 && segment.Count == segment.Array!.Length 
- ? System.Text.Encoding.UTF8.GetBytes(segment.Array) 
+ Blob = MemoryMarshal.TryGetArray(dc.Base64Data, out ArraySegment<char> segment)
+ ? System.Text.Encoding.UTF8.GetBytes(segment.Array!, segment.Offset, segment.Count) 
  : System.Text.Encoding.UTF8.GetBytes(dc.Base64Data.ToString())
  },