The key is to listen to your daughter, and you may have to invite her to speak. She may be too shy to bring it up, because it can feel like bragging to say, "I think Boy likes me." See how she feels, discuss what she wants and what you the parents want. Maybe brainstorm or role-play things she can say if needed.
We had a very similar situation, starting with a similar group of geeky neighbourhood teens, except that the boy was several years older than our 14yo daughter. We made him welcome in a friendly way, and he hung out at our house on his own as well as with the teen squad. We made a point of treating him in a friendly way: sometimes DD was the only one chatting with him, sometimes one or both of her brothers were there, sometimes there was a parent, too. Eventually it petered out (as you'd expect, since few teen crushes turn into lifelong loves). One day he told me how much he admired and liked DD. I was able to tell him frankly but kindly that she considered him a close friend but had no romantic feelings for him, nor any desire for a boyfriend at all at that point, and her father and I agreed that she was too young for a romantic relationship. He gradually hung out alone less often, but they have stayed friends.
[edited for typo]