Bug: FileCommand.Cancel() is a no-op that silently does nothing

[DaveRMaltby]

Summary

FileCommand.Cancel() only logs a debug message and does nothing. Since all operations are synchronous, there is no way to cancel an in-progress command. This is a correctness issue because Cancel() is part of the ADO.NET contract.

Location

• src/Data.Common/ADO.NET/FileCommand.cs:125-128

Current Behavior

public override void Cancel()
{
    log.LogDebug($"{GetType()}.{nameof(Cancel)} () called.");
}

Impact

• Long-running queries (e.g., scanning large CSV files) cannot be interrupted
• CommandTimeout is accepted as a property but never enforced