Flicker on swipe forward/back in mobile Safari

Low priority because mobile is low priority in general, plus this isn't broken, it just looks weird. Same issue as https://github.com/remix-run/react-router/issues/10883.

Noticed this while checking out the preview on my phone. When I use swipe gestures to go back and forward, I get a weird flicker. Say I'm on page A, I navigate to B, then I swipe back. First it loads its screenshot of what A looked like before (good), then it cuts back to what the page is currently showing (page B with a loading bar while page A's loaders run), then finally it lands back on showing A again once the RR nav happens. Using the back and forward buttons like in a desktop browser does not have this problem because there is no preview image being shown.

Apparently this is a pretty old issue with SPAs, judging by this 2014 SO question. There's a suggested workaround here that involves hacking scroll position to mess with how Safari decides what image to use for its preview of the previous page.

https://github.com/oxidecomputer/console/assets/3612203/3f808671-6914-45fc-91ba-de74b04d3ac9

No source file or test is identified in the issue. Start by reproducing the swipe back/forward flow on mobile Safari using the preview, then trace the navigation and loading behavior involved; done means the intermediate flicker no longer appears while desktop back and forward behavior remains unaffected.