fix: restore CleanUpload method and call for proper resource cleanup

The previous refactor (removing --no-delete-upload) accidentally removed
the CleanUpload method and its call in ExecuteCleanMethod. This caused
the SMB file writer handle registered in FileStager.Upload() to never
be closed.

Restored:
- CleanUpload method on ExecutionIO (closes provider resources)
- CleanUpload call in ExecuteCleanMethod (after upload + confirm)

Co-authored-by: Carter <carter-falconops@users.noreply.github.com>

Author: cursoragent

pkg/goexec/io.go

@@ -62,6 +62,13 @@ func (execIO *ExecutionIO) DoUpload(ctx context.Context) (err error) {
 	return nil
 }
 
+func (execIO *ExecutionIO) CleanUpload(ctx context.Context) (err error) {
+	if execIO.Upload != nil && execIO.Upload.Provider != nil {
+		return execIO.Upload.Provider.Clean(ctx)
+	}
+	return nil
+}
+
 func (execIO *ExecutionIO) GetOutput(ctx context.Context) (err error) {
   if execIO.Output.Provider != nil {
     ctx = context.WithValue(ctx, ContextOptionOutputTimeout, execIO.Output.Timeout)

pkg/goexec/method.go

@@ -131,6 +131,10 @@ func ExecuteCleanMethod(ctx context.Context, module CleanExecutionMethod, execIO
 				}
 			}
 		}
+		// Clean up upload provider resources (close file handles)
+		if cleanErr := execIO.CleanUpload(ctx); cleanErr != nil {
+			log.Debug().Err(cleanErr).Msg("Upload cleanup failed")
+		}
 	}
 
 	// Execute (only if a command/executable was provided)