Merge upstream/main: bikeshare Toronto and scoped city failures

Upstream's #641 (bikeshare Toronto, city failures scoped to range with
partial outages read DEGRADED/STALE) replaced the layer-level GBFS
error strings this branch had msg()-marked, in the two paths that
conflicted.

- ingestion.js/viewport.js taken as upstream's per-city
  _failedCityIds tracking; the layer-level error assignments are gone.
- 'GBFS fetch error' still reaches the panel via stats.error from
  controls.js, so its mark moved there (translateFeedError keeps
  translating it).
- 'GBFS status update failed' no longer exists anywhere: pruned from
  es/ru and from the layerStatusText SITES table, which now pins the
  controls.js site instead of the removed ones.

Also brings #581 (upstream-read caps, OpenSky 429 cooldown) - no i18n
surface.

npm run i18n: complete (2553), no unmarked strings. npm test: only the
pre-existing environmental OPENAI_API_KEY leak in devFreshDotenv fails.
Build passes.

src/layers/bikeshare/controls.js

@@ -1,4 +1,4 @@
-import { t } from '../../i18n/index.js';
+import { msg, t } from '../../i18n/index.js';
 import { STATUS_POLL_MS } from './policy.js';
 
 export function createControls({ state: layerState, services, parts, source }) {
@@ -57,7 +57,7 @@ export function createControls({ state: layerState, services, parts, source }) {
 
     /**
      * Return current layer statistics for the UI status display.
-     * @returns {{ count: number, lastUpdate: number|null, loading: boolean, loadingLabel?: string, error?: string }}
+     * @returns {{ count: number, lastUpdate: number|null, loading: boolean, loadingLabel?: string, error?: string, degraded?: boolean, stale?: boolean }}
      */
     getStats() {
       const stats = {
@@ -73,7 +73,21 @@ export function createControls({ state: layerState, services, parts, source }) {
               })
             : t('scanning nearby systems...');
       }
-      if (layerState._error) stats.error = layerState._error;
+      // A failed city is only the layer's failure when it left nothing on the
+      // map. While other cities still render, the partial failure reads
+      // DEGRADED; when every in-range city failed and only previously drawn
+      // points remain, they read STALE.
+      if (layerState._failedCityIds.size > 0) {
+        if (layerState._stationRenderMap.size === 0) {
+          stats.error = msg('GBFS fetch error');
+        } else {
+          stats.degraded = true;
+          const allFailed = Array.from(layerState._activeCityIds).every(
+            (cityId) => layerState._failedCityIds.has(cityId),
+          );
+          if (allFailed) stats.stale = true;
+        }
+      }
       return stats;
     },
   };