Summary

• switch SummaryHandler to log FlowSynxException with the structured LogError overload and a clear message instead of calling ToString()
• return the failure response with the exception message so clients see the intended error text without the formatted stack trace
• aligns logging with the rest of the codebase and closes Exception should be passed directly to logger instead of using ex.ToString() #743

Testing

• dotnet test FlowSynx.sln