Hold Cockpit regional news to the last 24 hours, and tell its states apart

Regional News showed "REGIONAL NEWS UNAVAILABLE" above populated rows and a
static "RECENT" footer over months-old articles. The status banner kept
`display: grid` when hidden, every non-empty answer carried the unavailable
text, and nothing limited or sorted articles by age.

- One window (regionalNewsWindow.js, 24 h): the local proxy asks Google News
  with `when:1d` and GDELT for 24 h, drops undated, older or future-dated
  articles, sorts newest first, and reports newsWindowHours/newsFetchedAt.
- The Cockpit labels four states: fresh (banner hidden, "LAST 24 H"),
  kept after a failed refresh ("CACHED · REFRESH FAILED"), no news in the
  window, and unavailable. The footer lives in the news state, so it
  survives page and tab changes, and the client drops out-of-window rows.
- `.cockpit-brief-status[hidden]` now hides the banner.

server/providers/regional/briefing.js

@@ -3,6 +3,7 @@ import { fetchRegionalPlace } from './place.js';
 import { fetchRegionalWeather } from './weather.js';
 import { fetchRegionalNews } from './news.js';
 import { validRegionalPoint } from './query.js';
+import { REGIONAL_NEWS_WINDOW_HOURS } from '../../../src/data/regionalModel.js';
 import { coalesceProxyRequest } from '../common/http.js';
 
 // ---------------------------------------------------------------------------
@@ -50,10 +51,11 @@ function regionalBriefProxy({ placeProvider = fetchRegionalPlace } = {}) {
     if (!regionalBriefHasAnySource({ place, weather, news })) {
       throw new Error('All regional briefing sources unavailable');
     }
+    const retrievedAt = new Date().toISOString();
     const payload = {
       status:
         place && weather && news.status !== 'unavailable' ? 'ready' : 'partial',
-      retrievedAt: new Date().toISOString(),
+      retrievedAt,
       coordinates: point,
       place,
       placeStatus: place ? 'ready' : 'unavailable',
@@ -62,6 +64,9 @@ function regionalBriefProxy({ placeProvider = fetchRegionalPlace } = {}) {
       newsStatus: news.status,
       newsQuery: news.query,
       newsSource: news.source,
+      newsWindowHours: REGIONAL_NEWS_WINDOW_HOURS,
+      // A cached or stale answer keeps this, so the client can show its age.
+      newsFetchedAt: retrievedAt,
       articles: news.articles,
     };
     _regionalBriefCache.set(key, { payload, cachedAt: Date.now() });