Present search results as a separate page, not a popup?

I forget who exactly requested this, but in order to track it. This would presumably be more like what [docs.python.org](https://docs.python.org/3/search.html?q=quantum) does - search results come up as a separate page in the content pane, rather than as a popup. I asked on [the Antora chat](https://antora.zulipchat.com/#narrow/stream/312271-users.2Flunr-extension/topic/Non-popup.20search.20results.20page.3F/near/396652397) and it is apparently not built-in behavior in the antora-lunr integration, but probably not overly complex to add for someone conversant with antora-lunr and with the Antora content model. As with many "site should do this, not that" requests it probably means adding some sort of UI preferences, presumably persistent across sessions.

Start by reviewing the antora-lunr integration and the Antora content model, using the docs.python.org search page and the linked Antora chat discussion as behavioral references. Define how search results should appear in the content pane and how any UI preference persists across sessions; done means the site presents results on a separate page instead of a popup.

Written by the indexing model from the issue text.