Add ability to silence input prompts when using file interaction

If I redirect stdin so that inputs are read from a file, the input prompts are still displayed to stdout (with newlines chopped off). This looks rather ugly and amateurish. I'd like to be able to configure the prompt functionality to only prompt in interactive mode.

Start by locating the file-interaction path that writes input prompts and the existing interactive-mode configuration. Check how redirected stdin is detected, then define and test the behavior: prompts remain in interactive mode but are suppressed when input comes from a file.

Written by the indexing model from the issue text.