fix(status): stop false LOAD FAILED from a relayed adsb.lol 429 and the installations zoom prompt

Two independent triggers turned the global status chip red while every layer
was still populated (reproduced at JFK in Cockpit; timeline in the issue).

adsb.lol proxy: a non-OK upstream status was relayed verbatim even with a
12 s-old cache in hand, and the browser layer answers a 429 with a 45 s
cooldown in which every refresh reports "adsb.lol rate limited" without a
network call. The proxy now serves its cached body as STALE on a 429/5xx and
backs off from upstream for Retry-After (bounded), mirroring the OpenSky
proxy. A failure with nothing cached is still relayed.

Mapped installations: the "zoom in" guidance was stored in `error`, so the
manager reported a refresh failure and the chip a LOAD FAILED whenever the
view could not be bounded (Cockpit looks at the horizon). The status is now
set without an error string; the row reads the prompt from `statusMessage`,
and the chip ignores `error` for guidance statuses, matching the carve-out
layerFeedState already has.

src/loadingFeedback.test.mjs

@@ -685,3 +685,17 @@ test('the loading ticker never runs hidden and stops after loading and notices s
     'the resample handler must be removed on teardown',
   );
 });
+
+test('a guidance status such as zoom-in never counts as a participant failure', () => {
+  const zoomIn = { id: 'military-installations', name: 'Mapped Installations', enabled: true,
+    stats: { status: 'zoom-in', error: 'Zoom in to load mapped installation context', loading: true, count: 0 } };
+  const loading = aggregateLayerLoading([zoomIn]);
+  assert.equal(loading.records[0].error, null);
+  assert.equal(loading.records[0].degraded, false);
+  let state = reduceLoadingFeedback(createLoadingFeedbackState(), loading, 1000);
+  state = reduceLoadingFeedback(state, loading, 1200);
+  const settled = aggregateLayerLoading([{ ...zoomIn, stats: { ...zoomIn.stats, loading: false } }]);
+  state = reduceLoadingFeedback(state, settled, 1500);
+  assert.equal(state.terminal, 'complete');
+  assert.equal(presentLoadingFeedback(state, settled, 1500).label, 'MAPPED SITES LOADED');
+});