Add comprehensive GitHub Copilot instructions for LogExpert repository onboarding - #467

'success == false' is always 'false'. Remove or refactor the condition(s) to avoid dead code. (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1508)

'_sftp != null' is always 'true'. Remove or refactor the condition(s) to avoid dead code. (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1508)

'privateKeyFile != null' is always 'true'. Remove or refactor the condition(s) to avoid dead code. (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1508)

Modify 'GetLogfileInfo' to catch a more specific allowed exception type, or rethrow the exception (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1031)

Modify 'CanHandleUri' to catch a more specific allowed exception type, or rethrow the exception (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1031)

Modify 'get_FileExists' to catch a more specific allowed exception type, or rethrow the exception (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1031)

The type name AutoColumnizer conflicts in whole or in part with the namespace name 'AutoColumnizer'. Change either name to eliminate the conflict. (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1724)

Change the type of parameter 'uriString' of method 'IFileSystemPlugin.GetLogfileInfo(string)' from 'string' to 'System.Uri', or provide an overload to 'IFileSystemPlugin.GetLogfileInfo(string)' that allows 'uriString' to be passed as a 'System.Uri' object (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1054)

Change the type of parameter 'uriString' of method 'IFileSystemPlugin.CanHandleUri(string)' from 'string' to 'System.Uri', or provide an overload to 'IFileSystemPlugin.CanHandleUri(string)' that allows 'uriString' to be passed as a 'System.Uri' object (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1054)

Nullability of type of parameter 'obj' doesn't match overridden member (possibly because of nullability attributes).