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/utils/resolvePlaybackUrl.ts

@@ -2,6 +2,57 @@ import { buildStreamUrl } from '../api/subsonic';
 import { useOfflineStore } from '../store/offlineStore';
 import { useHotCacheStore } from '../store/hotCacheStore';
 
+/** Same resolution order as {@link resolvePlaybackUrl} — for UI hints only. */
+export type PlaybackSourceKind = 'offline' | 'hot' | 'stream';
+
+/**
+ * Subsonic `buildStreamUrl()` rotates `t`/`s` on every call; Rust matches by `id` (see `playback_identity`).
+ */
+export function streamUrlTrackId(url: string): string | null {
+  if (!url.includes('stream.view')) return null;
+  try {
+    const fromUrl = new URL(url).searchParams.get('id');
+    if (fromUrl) return fromUrl;
+  } catch {
+    // Fallback for non-standard/relative URLs: parse query manually.
+  }
+  const q = url.split('?')[1];
+  if (!q) return null;
+  for (const part of q.split('&')) {
+    const [k, v = ''] = part.split('=');
+    if (k === 'id') {
+      try {
+        return decodeURIComponent(v);
+      } catch {
+        return v;
+      }
+    }
+  }
+  return null;
+}
+
+/**
+ * @param enginePreloadedTrackId — song id for which `audio_preload` finished into the engine RAM slot
+ *   (parsed from `audio:preload-ready` payload URL).
+ */
+export function getPlaybackSourceKind(
+  trackId: string,
+  serverId: string,
+  enginePreloadedTrackId: string | null = null,
+): PlaybackSourceKind {
+  if (useOfflineStore.getState().getLocalUrl(trackId, serverId)) return 'offline';
+  if (useHotCacheStore.getState().getLocalUrl(trackId, serverId)) return 'hot';
+  const resolved = resolvePlaybackUrl(trackId, serverId);
+  if (
+    !resolved.startsWith('psysonic-local://')
+    && enginePreloadedTrackId
+    && trackId === enginePreloadedTrackId
+  ) {
+    return 'hot';
+  }
+  return 'stream';
+}
+
 /** Offline library → hot playback cache → HTTP stream. */
 export function resolvePlaybackUrl(trackId: string, serverId: string): string {
   const offline = useOfflineStore.getState().getLocalUrl(trackId, serverId);