AskUserQuestion: markdown preview mode removes custom text input field

When using AskUserQuestion with the markdown field on options (preview mode), the custom text input ("Other") field disappears. The user can only select from predefined options and cannot provide free-form feedback.

Expected behavior: The custom text input field should always be available regardless of whether markdown previews are used.

Actual behavior: In preview mode (side-by-side layout with option list + preview panel), there is no way for the user to type custom text. They can only select one of the predefined options.

Workaround: Don't use markdown previews when custom feedback is needed. Use plain options with descriptions instead.