feat(queue): show playback source in tech strip with preload tracking

Add source badges for offline, cache, and stream playback in the queue tech line, including localized tooltips across shipped locales.

Track Rust preload-ready events by stream track id and latch the selected source per track, with dev logs to debug preload/source mismatches during next-track handoff.

src/locales/en.ts

@@ -855,6 +855,9 @@ export const enTranslation = {
     rgTrack: 'T {{db}} dB',
     rgAlbum: 'A {{db}} dB',
     rgPeak: 'Peak {{pk}}',
+    sourceOffline: 'Playing from offline library',
+    sourceHot: 'Playing from cache',
+    sourceStream: 'Playing from network stream',
   },
   statistics: {
     title: 'Statistics',