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/de.json

@@ -1667,6 +1667,9 @@
   "Hybrid": "Hybrid",
   "TomTom key unavailable": "TomTom-Schlüssel nicht verfügbar",
   "TomTom daily budget reached": "TomTom-Tagesbudget erreicht",
+  "Monthly traffic allowance used": "Monatliches Verkehrskontingent aufgebraucht",
+  "Traffic rate limit reached": "Verkehrs-Anfragelimit erreicht",
+  "Traffic service unavailable": "Verkehrsdienst nicht verfügbar",
   "TomTom upstream unreachable": "TomTom-Upstream nicht erreichbar",
   "TomTom flow unavailable": "TomTom-Verkehrsfluss nicht verfügbar",
   "SIMULATED — {reason}": "SIMULIERT – {reason}",