fix(layers): translate every route proxy refusal and clear stale receiver errorText

The route proxy also refuses with 'routing busy — too many routes at once'
(429) and 'route proxy error'; both showed in English in every locale.
Mark them in ROUTING_REFUSALS and add es, ru, zh-CN and zh-Hant entries.

errorText is now cleared on a new connection, a mode switch and stop(), so
it never outlives the error it describes. Tests cover the two refusals,
'Routing failed: rate limited' (pattern order) and the stop() reset.

src/i18n/locales/es.json

@@ -3001,5 +3001,7 @@
   "Your choice applies now, but could not be saved.": "Tu elección se aplica ahora, pero no se pudo guardar.",
   "Voice replies appear here.": "Las respuestas de voz aparecen aquí.",
   "Preview is off.": "La vista previa está desactivada.",
-  "Automatic stop is unavailable for this voice connection.": "La parada automática no está disponible para esta conexión de voz."
+  "Automatic stop is unavailable for this voice connection.": "La parada automática no está disponible para esta conexión de voz.",
+  "routing busy — too many routes at once": "servicio de rutas ocupado: demasiadas rutas a la vez",
+  "route proxy error": "error del proxy de rutas"
 }