Video from previous page autoplays when going back

When visiting a page with a `video` element with the `autoplay` element via a boosted link, then navigating back, the video's audio will autoplay on the "old" page, even though the video isn't anywhere in the DOM.

Fiddle: https://jsfiddle.net/st0oLudr/
```html

Click me to see a video!

```

Click the link, then click the browser back button.

No idea how this works. Is the video is still playing outside of the DOM somehow?

Start with the JSFiddle reproduction and trace htmx boosted-link navigation followed by the browser Back action, focusing on what happens to the old page's video. Done means reproducing the case and preventing audio from the previous page from autoplaying after Back, with regression coverage for that behavior.

Written by the indexing model from the issue text.