It's not totally unambiguous, but there's a strong hint there. However, not everyone who invites someone for coffee or lunch necessarily wants to get in the other person's pants.

You'll just have to gage her reaction. Has she answered yet? If she accepts your invitation, you can make it clearer during your "date". Just because she is willing to have coffee or lunch with you doesn't necessarily mean she wants to date you. If she acts like she likes your company, all signs point to her being interested. But you have to say it in a clearer way, eventually.