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/ui/statusText.js

@@ -122,6 +122,8 @@ const ROUTING_REFUSALS = new Set([
   msg('routing service is rate limited'),
   msg('route leg too long'),
   msg('route too long'),
+  msg('routing busy — too many routes at once'),
+  msg('route proxy error'),
 ]);
 const routingRefusal = (text) =>
   ROUTING_REFUSALS.has(text) ? t(text) : translateKnown(text);