- migration 202610280003: settings links_new_tab (default on),
nofollow_domains and sponsored_domains; robots llms_enabled and
llms_intro (used by the llms.txt commit)
- SEO settings Links tab: the new-tab switch and the two domain lists,
one domain per line, lowercased, refused with settings.domain_invalid
naming the line; writable through seo_update_settings
- the resolve answer of an ok page carries outbound {new_tab,
nofollow_domains, sponsored_domains}; no existing key changes
