fix(nav): the dead-page rewrite does not restore a spent focus stamp

It spread the event's snapshot, which still carried the sfNav stamp lib/history's own listener had
just taken off the entry, so a later landing there (an overlay closing) refocused a stale item. It
now spreads the live entry (test red on the snapshot). Also: format.test's comment named a test
image that never runs vitest; it is the gate host's locale.

frontend/src/lib/format.test.ts

@@ -132,8 +132,8 @@ describe("relativeFromMs", () => {
 // A bare `n.toLocaleString()` groups in the BROWSER's locale, so an English UI in a Hungarian browser
 // printed "1 234 567" (and a Hungarian UI in an English browser "1,234,567"). The case below asserts
 // BOTH languages and that the two differ, rather than comparing against the runtime's own default:
-// the default is whatever locale the machine running the suite has (Hungarian on the dev box, English
-// in the test image), so a one-language assertion passes under the old bug on half the machines.
+// the default is whatever locale the host running the gate has (Hungarian on the dev box, English or
+// C on a Linux host), so a one-language assertion passes under the old bug on half the machines.
 describe("formatNumber", () => {
   afterEach(() => {
     i18nStub.language = "en";