The house I am buying has some upper story bedroom windows which I'm
trying to figure out how to childproof.

They swing open outward but no cranks, and have no screens.

The short term option is going to be just wiring them shut.

Once it gets warmer, I would like to have the option of installing
screens, plus whatever additional childproofing is possible to let the
windows be used.

I'm reluctant to put in burglar proofing bars because that will make the
windows impossible to use if there is a fire. The window frame isn't
deep enough to accept the typical removable child gate that I use to
temporarily block doorways.

Because the windows open out, I'm also reluctant to use some
childproofing options I've seen which allow the windows to open just
partway. I'm sure that a kid who leaned all of his weight against the
windows could force the windows open.

So, is there some type of childproofing option which I can install on
these windows? I'm hoping for something which allows for the windows to
open, accepts screens, can be removed quickly by an adult, but not by a
child.