fix(zh-CN): localize readouts and keep short labels intact

Preserve Chinese unit casing and spacing in the HUD and cockpit, localize FIRMS cache ages, CCTV health and radio counts, and keep imagery resolution and route modes readable. Add regression coverage for localized output and unchanged English.

Co-Authored-By: Codex (GPT-6) <[email protected]>

src/layers/firms/model.js

@@ -591,6 +591,7 @@ export function createModel({
     formatLatLon,
     formatFrp,
     formatAge,
+    formatAgeLabel,
     formatAgoMinutes,
     confidenceBucket,
   };

src/layers/firms/queries.js

@@ -64,7 +64,8 @@ export function createQueries({
       const staleText = layerState._lastUpdate
         ? t('STALE · cached {age}', {
             age:
-              components.model.formatAge(now - layerState._lastUpdate) || '<1h',
+              components.model.formatAgeLabel(now - layerState._lastUpdate) ||
+              t('<1h', { context: 'age' }),
           })
         : t('STALE');
       let loadingLabel = '';

src/layers/recentImagery/display.js

@@ -3,7 +3,12 @@
  * day's readout. The model (`model.js`) stays English and i18n-free because AI
  * tool services import it outside the browser; this module is page-only.
  */
-import { formatDate, formatRelativeTime, t } from '../../i18n/index.js';
+import {
+  formatDate,
+  formatRelativeTime,
+  getLocale,
+  t,
+} from '../../i18n/index.js';
 import { formatQuantity } from '../../ui/unitLabels.js';
 import { dayTime } from './model.js';
 
@@ -26,7 +31,10 @@ export const displayMetres = (value) => formatQuantity(value, 'm');
 /** The readout's words in the page's language; the model keeps them English. */
 export const READOUT_WORDS = Object.freeze({
   date: (day) => displayDay(day, LONG_DAY),
-  daysAgo: (delta) => formatRelativeTime(delta > 0 ? -delta : 0, 'day'),
+  daysAgo: (delta) => {
+    const text = formatRelativeTime(delta > 0 ? -delta : 0, 'day');
+    return getLocale() === 'zh-CN' ? text.replace(/(\d)(?=天)/g, '$1 ') : text;
+  },
   // "Sentinel-2" never breaks at its hyphen: a word joiner follows it
   // (JetBrains Mono has no U+2011 non-breaking hyphen).
   sensor: (sensor) =>