fix(traffic): name an account's traffic limit instead of a daily budget

A failed flow tile now carries the server's reason. A hosted deployment that limits each account answers USAGE_LIMIT_REACHED or RATE_LIMITED, which the traffic panel labels as the monthly allowance or a rate limit; a 503 with another reason reads as the traffic service being unavailable, not a missing key. The local proxy's no_key and daily budget labels are unchanged.

src/i18n/locales/fr.json

@@ -1105,6 +1105,9 @@
   "Hybrid": "Hybride",
   "TomTom key unavailable": "Clé TomTom indisponible",
   "TomTom daily budget reached": "Quota quotidien TomTom atteint",
+  "Monthly traffic allowance used": "Quota mensuel de trafic épuisé",
+  "Traffic rate limit reached": "Limite de requêtes de trafic atteinte",
+  "Traffic service unavailable": "Service de trafic indisponible",
   "TomTom upstream unreachable": "Serveur TomTom injoignable",
   "TomTom flow unavailable": "Flux TomTom indisponible",
   "SIMULATED — {reason}": "SIMULÉ — {reason}",