NodeBB image uploader comes from a plugin or is it a core feature? I can't seem to find it. I want to use a small vanilla js script to add a lightbox to uploaded images. I could add a class dinamically with js, I guess but I'd rather add it to the image output.
I don't know how to do it in another way.
You're not able to change the routing in such a way, because then users whose names are only numbers cannot be accessed.
Best bet is to set up a rewrite rule in nginx to send users requesting /user/\d+ to /uid/1