Dashboard admin : split stats/disk + preload disk au warmup + wc -l (1.85s -> 40ms)

server.js

@@ -10,6 +10,7 @@ import { preloadMappings } from './lib/imdbMapping.js';
 import { getRatings } from './lib/imdbRatings.js';
 import { httpDuration, httpRequests, imdbRatingsCount, searchWorkers } from './lib/metrics.js';
 import { getPool } from './lib/searchEngine.js';
+import { preloadDiskUsage } from './lib/stats.js';
 import adminRoutes from './routes/admin.js';
 import apiRoutes from './routes/api.js';
 import healthRoutes from './routes/health.js';
@@ -84,9 +85,12 @@ fastify.ready().then(async () => {
     searchWorkers.set({ type: 'tv' }, tv.workers.length);
     const maps = await preloadMappings();
     startWatchers();
+    // Disk usage takes ~3 s on cold cache (du -sb on 1.7M files). Run it in
+    // background so the first admin visitor finds the result already cached.
+    preloadDiskUsage();
     fastify.log.info(
       { ratings: ratings.size, imdb_movie: maps.movie, imdb_tv: maps.tv },
-      'Warmup complete (data hot-reload watchers started)',
+      'Warmup complete (data hot-reload watchers started, disk usage preloading)',
     );
   } catch (err) {
     fastify.log.warn({ err }, 'Warmup failed');