feat: links settings and outbound rules in resolve

- 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

settings_test.go

@@ -31,7 +31,7 @@ func TestSettingsTypeTabs(t *testing.T) {
 		env := bootEnv(t)
 		token := env.admin(t, true)
 		fields := env.formSchema(t, token, "golem15/seo/settings")
-		if got, want := strings.Join(tabsOf(fields), " | "), "General | Page | Tags | Notes | Site page | Indexing | Addresses | Verification"; got != want {
+		if got, want := strings.Join(tabsOf(fields), " | "), "General | Page | Tags | Notes | Site page | Indexing | Addresses | Links | Verification"; got != want {
 			t.Fatalf("settings tabs = %q, want %q", got, want)
 		}
 		findField(t, fields, "type_acme_page_inject")
@@ -81,7 +81,7 @@ func TestSettingsTypeTabs(t *testing.T) {
 	t.Run("no other content types", func(t *testing.T) {
 		env := bootPlugins(t, []string{"golem15.seo"})
 		token := env.admin(t, true)
-		if got, want := strings.Join(tabsOf(env.formSchema(t, token, "golem15/seo/settings")), " | "), "General | Site page | Indexing | Addresses | Verification"; got != want {
+		if got, want := strings.Join(tabsOf(env.formSchema(t, token, "golem15/seo/settings")), " | "), "General | Site page | Indexing | Addresses | Links | Verification"; got != want {
 			t.Fatalf("settings tabs = %q, want %q", got, want)
 		}
 	})