Hi OP,
It sounds like you have a really close and meaningful friendship — and her sharing that dream with you, followed by the comment “If the thought ever entered your mind, you know my response” definitely hints at something more than casual friendship.
While it’s not “irrefutable proof” in a scientific sense, it is a pretty strong indicator that she’s open to something deeper if you are. That kind of statement usually doesn’t come out of nowhere — especially from someone mature who values clarity.
If you’re comfortable, you could gently follow up with her and say something like, “I’ve been thinking about what you said the other day. Did you mean it as a joke, or were you serious?” — and see how she responds.
Best of luck, and well done for reaching out — navigating emotions is tough for anyone, autistic or not.