Yay, now it works. Not sure the best way to show loading yet.
- currently the Turbo loading indicator shows which is better than nothing (blue bar at top)
- ideally we could show a small spinner over the image thumbnail. need to write some stimulus to hook into turbo lifecycle I guess.
- or we could activate the frame-level loading overlay. refactor loading_controller a bit so that it's applied on the container, then hopefully we can just call change->loading#showLoading. the turbo_stream response could dectivate it.
This could have been done with a tiny amount of inline JS, but I went this way in case I needed any special logic for UJS. It turns out we don't.. but it still looks a bit cleaner this way.
