How do I fill the holes in concrete to reattach a curtain rod?
You might have to use one of these drop-in anchors with an embed sucket. Enlarge the existing hole, if it is smaller than the sucket, and install the sucket with recommended adhesive. If the existing hole is larger than the sucket, clean the hole and fill it with mortar paste and the sucket. Do not install the curtain rod holder until the adhesive/mortar has fully cured. https://www.globalindustrial.com/c/fasteners/Anchors

For the edge, I'll just paint it over.