fix(voice): keep a stopped round's actions and follow-up memory

A reply stopped partway through a round now keeps the actions that ran,
answering the calls it never reached as skipped, so the history stays
paired for both providers. A failed typed turn no longer resets the
pointer, referents and follow-up memory, since its conversation continues.

The server now tells a rejected key (401, or Gemini's 400 with reason
API_KEY_INVALID, matched exactly), denied access (403) and an account out
of credit (OpenAI's 429 insufficient_quota) apart; each cools down for a
minute and gets its own message in the chat.

src/i18n/locales/de.json

@@ -3013,5 +3013,7 @@
   "That request needed too many steps. Changes already made to the map stay in place.": "Diese Anfrage brauchte zu viele Schritte. Bereits vorgenommene Kartenänderungen bleiben erhalten.",
   "That request needed too many steps. Try a simpler request.": "Diese Anfrage brauchte zu viele Schritte. Versuche eine einfachere Anfrage.",
   "The provider rejected the API key. Check it in Provider Settings.": "Der Anbieter hat den API-Schlüssel abgelehnt. Prüfe ihn in den Anbieter-Einstellungen.",
-  "Too many chat requests. Try again in {seconds} s.": "Zu viele Chat-Anfragen. In {seconds} s erneut versuchen."
+  "Too many chat requests. Try again in {seconds} s.": "Zu viele Chat-Anfragen. In {seconds} s erneut versuchen.",
+  "The provider refused access for this key. Check the key's project, region or permissions.": "Der Anbieter hat den Zugriff für diesen Schlüssel verweigert. Prüfe Projekt, Region oder Berechtigungen des Schlüssels.",
+  "The provider account is out of credit. Check its billing, or choose another AI Provider in Settings.": "Das Anbieterkonto hat kein Guthaben mehr. Prüfe die Abrechnung oder wähle in den Einstellungen einen anderen KI-Anbieter."
 }