fix: report stale and partial data in more tool answers

A sweep for the same pattern found more answers presented as current and
complete: launches and satellite orbits served from a stale proxy cache, a
regional aircraft fallback read as worldwide, license plate cameras trimmed
or partly loaded, and a radio directory of popular stations read as every
station. The launch and satellite sources now report the proxies' stale
markers, and each answer says what it covers.

src/layers/launches/source.js

@@ -2,16 +2,24 @@
 export function createLaunchSource({
   fetchImpl = (...args) => globalThis.fetch(...args),
 } = {}) {
+  /** The launch payload, and whether the proxy served it from a stale cache. */
+  async function getLaunchSnapshot({ signal } = {}) {
+    signal?.throwIfAborted();
+    const response = await fetchImpl('/api/launches', { signal });
+    if (!response.ok) throw new Error(`HTTP ${response.status}`);
+    const payload = await response.json();
+    signal?.throwIfAborted();
+    if (!Array.isArray(payload) && !Array.isArray(payload?.results))
+      throw new Error('Malformed launch snapshot');
+    return {
+      payload,
+      stale: response.headers?.get?.('x-gev-cache') === 'STALE-ERROR',
+    };
+  }
   return {
-    async getLaunches({ signal } = {}) {
-      signal?.throwIfAborted();
-      const response = await fetchImpl('/api/launches', { signal });
-      if (!response.ok) throw new Error(`HTTP ${response.status}`);
-      const payload = await response.json();
-      signal?.throwIfAborted();
-      if (!Array.isArray(payload) && !Array.isArray(payload?.results))
-        throw new Error('Malformed launch snapshot');
-      return payload;
+    getLaunchSnapshot,
+    async getLaunches(options) {
+      return (await getLaunchSnapshot(options)).payload;
     },
     async getActiveTle({ signal } = {}) {
       signal?.throwIfAborted();

src/layers/satellites/source.js

@@ -19,7 +19,10 @@ export function createSatelliteSource({
       const response = await fetchImpl(`/api/celestrak/${group}`, { signal });
       const text = response.ok ? await response.text() : '';
       signal?.throwIfAborted();
-      return { ok: response.ok, status: response.status, text };
+      // The proxy serves its last copy, marked STALE-ERROR, when CelesTrak
+      // is down.
+      const stale = response.headers?.get?.('x-tle-cache') === 'STALE-ERROR';
+      return { ok: response.ok, status: response.status, text, stale };
     },
   };
 }