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/zh.ts

@@ -846,6 +846,9 @@ export const zhTranslation = {
     rgTrack: '曲目 {{db}} dB',
     rgAlbum: '专辑 {{db}} dB',
     rgPeak: '峰值 {{pk}}',
+    sourceOffline: '正在从离线库播放',
+    sourceHot: '正在从缓存播放',
+    sourceStream: '正在从网络流播放',
   },
   statistics: {
     title: '统计',