Configure the LLM provider for the embedded agent. Providers are
shared across all apps (sovereign_browser, client, didactyl) via the
Nostr d:user-settings event. The model, system prompt,
and max iterations are per-app. Type a semicolon then a message in
the URL bar to talk to the agent.
The system prompt is treated as the default skill for sovereign_browser. Edit it here, then click "Save as Skill" to publish it to Nostr as a kind 31123 event (shareable with client, didactyl, and other apps).