user form, backup: two gaps the mockup comparison found

Owner, 2026-10-18: "Что ещё из макетов мы также прошляпили?" - every mockup
held against the panel; two small gaps beyond the queues:

- user.html: with All ticked, a list's single domains are disabled
  (mockup user.html:34-36). A panel.js show-when rule with disable: the
  boxes data-single-out / data-single-in follow data-all-out / data-all-in,
  at load and on change; a disabled box is not submitted, which the server
  ignores with All anyway. node test testdata/alldomains_test.js (fails on
  the previous panel.js).
- backup.html: "domain's settings" is a link, to Outbound › Domains (mockup
  backup.html:35 links a domain's settings; a server page has no one domain).

Tests: go test ./internal/web/... pass, TestPanelJS with node 24.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/web/view/paneljs_test.go

@@ -17,7 +17,7 @@ func TestPanelJS(t *testing.T) {
 	if err != nil {
 		t.Skip("node is not installed")
 	}
-	for _, script := range []string{"poll_test.js", "unsaved_test.js", "filename_test.js"} {
+	for _, script := range []string{"poll_test.js", "unsaved_test.js", "filename_test.js", "alldomains_test.js"} {
 		t.Run(script, func(t *testing.T) {
 			out, err := exec.Command(node, filepath.Join("testdata", script), filepath.Join("static", "panel.js")).CombinedOutput()
 			if err != nil {