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/components/QueuePanel.tsx

@@ -1,6 +1,6 @@
 import React, { useState, useRef, useMemo } from 'react';
 import { Track, usePlayerStore, songToTrack } from '../store/playerStore';
-import { Play, Music, Star, X, Trash2, Save, FolderOpen, Shuffle, Infinity, Waves, MicVocal, ListMusic, Check, ListPlus, ArrowUpToLine, Radio } from 'lucide-react';
+import { Play, Music, Star, X, Trash2, Save, FolderOpen, Shuffle, Infinity, Waves, MicVocal, ListMusic, Check, ListPlus, ArrowUpToLine, Radio, HardDrive } from 'lucide-react';
 import { buildCoverArtUrl, coverArtCacheKey, getAlbum, getPlaylists, getPlaylist, updatePlaylist, deletePlaylist, SubsonicPlaylist } from '../api/subsonic';
 import { usePlaylistStore } from '../store/playlistStore';
 import { useCachedUrl } from './CachedImage';
@@ -251,6 +251,8 @@ export default function QueuePanel() {
   const enqueueAt = usePlayerStore(s => s.enqueueAt);
   const contextMenu = usePlayerStore(s => s.contextMenu);
 
+  const playbackSource = usePlayerStore(s => s.currentPlaybackSource);
+
   const crossfadeEnabled = useAuthStore(s => s.crossfadeEnabled);
   const crossfadeSecs = useAuthStore(s => s.crossfadeSecs);
   const gaplessEnabled = useAuthStore(s => s.gaplessEnabled);
@@ -450,8 +452,29 @@ export default function QueuePanel() {
             ].filter(Boolean) as string[];
             const rgParts = formatQueueReplayGainParts(currentTrack, t);
             const techLine = [...baseParts, ...rgParts].join(' · ');
-            if (!techLine) return null;
-            return <div className="queue-current-tech">{techLine}</div>;
+            if (!techLine && !playbackSource) return null;
+            return (
+              <div className="queue-current-tech">
+                {playbackSource && (
+                  <span
+                    className="queue-current-tech-source"
+                    title={
+                      playbackSource === 'offline'
+                        ? t('queue.sourceOffline')
+                        : playbackSource === 'hot'
+                          ? t('queue.sourceHot')
+                          : t('queue.sourceStream')
+                    }
+                    aria-hidden
+                  >
+                    {playbackSource === 'offline' && <FolderOpen size={11} strokeWidth={2.25} />}
+                    {playbackSource === 'hot' && <HardDrive size={11} strokeWidth={2.25} />}
+                    {playbackSource === 'stream' && <Waves size={11} strokeWidth={2.25} />}
+                  </span>
+                )}
+                <span className="queue-current-tech-main">{techLine}</span>
+              </div>
+            );
           })()}
           <div className="queue-current-track-body">
             <div className="queue-current-cover">