Enhancement for Jetpack Search: Improve UX for Search when Blog pages show at most is not 10

### Impacted plugin

Search

### What

Do not modify the number of loaded search results if user sets **WP Admin > Settings > Reading > Blog pages show at most** different than 10.

### How

When a site is configured to display a custom number of posts (**WP Admin > Settings > Reading > Blog pages show at most** is different than default 10) it may create a bad experience.
If the screen is not high enough, the scroll trigger/load more button is not visible and there are empty slots that suggest no more items. See image:

Could we keep the number of search items aligned with the layout, always 10? Or adapt the layout?

Thank you!

---

Workarounds:

- Switch back settings to 10 in **WP Admin > Settings > Reading > Blog pages show at most** or adding this snippet:
- Custom CSS like this one that applies for 12 posts:

```
@media(min-width: 1400px) {
li.jetpack-instant-search__search-result.jetpack-instant-search__search-result-product {
width:calc(16.666% - 16px);
}
}
```

Start by locating Jetpack Search's result layout and load-more/scroll-trigger behavior, then trace how the WordPress “Blog pages show at most” setting affects the number of results. Reproduce the reported empty slots and hidden load-more control with a non-default setting; done means search results remain aligned with the layout and users can continue loading results.

Written by the indexing model from the issue text.