Can one keyword have mixed intent?

Yes, and Google shows mixed results for it. Classify by the dominant pattern and check the SERP to confirm.

Yes, transparent word-pattern rules. It is a planning heuristic, fast and free, not a machine learning model.

Where does intent fit in the workflow?

After keyword research, before outlining: intent picks the page type, then the brief fills in the content.

Type a keyword and the tool labels its likely intent using the word patterns real searches follow, with the reasoning shown.

Intent decides the page type before a single word is written. A transactional keyword on a blog post is a page that can never win.