Inability to handle authentication scripts is due to the web toolkit that Scrivener uses, which is more of a “viewer” than a full-fledged browser. Modern computers are generally very good at multitasking, though.
FWIW, “does Scrivener scrape my data for AI training” questions (no, we do not) are much more common than “how can I use an LLM in Scrivener” questions. Your belief that these tools are essential is not at all universally shared.