feat(mobile): queue track reactions made offline and sync on reconnect (M5)

Likes and dislikes without a network are kept in a pending_reactions
table (last reaction per track wins) and sent when the connection
returns, instead of being rolled back. Downloaded track DTOs pick up the
new reaction so the offline wave and Downloads reflect it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/mobile/src/offline/downloads.ts

@@ -192,6 +192,16 @@ class Downloads {
     this.pump();
   }
 
+  /** Реакция в сохранённом DTO: офлайн-волна и списки скачанного видят её без сети. */
+  async setReaction(trackId: string, reaction: Track['reaction']) {
+    const it = this.current.items.get(trackId);
+    if (!it || it.track.reaction === reaction) return;
+    const track = { ...it.track, reaction };
+    this.setItem(trackId, { track });
+    const db = await getDb();
+    await db.runAsync('UPDATE downloads SET track = ? WHERE owner = ? AND track_id = ?', JSON.stringify(track), this.owner, trackId);
+  }
+
   /** Повторить загрузки с ошибкой. */
   async retry() {
     const db = await getDb();