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/layers/localAdsb/statusLocale.test.mjs

@@ -99,6 +99,10 @@ for (const locale of ['es', 'ru']) {
       const row = rowFor(status, 0);
       assert.ok(row.includes(state.message), row);
       assert.doesNotMatch(row, /No RTL-SDR device selected/, row);
+
+      // The English text goes with the error: stop() clears it.
+      await receiver.stop();
+      assert.equal(receiver.getState().errorText, null);
     } finally {
       setLocale('en');
       await receiver.destroy();