feat(frontend): live-refresh song list during S3 sync so newly matched tracks show play button immediately

- BackgroundJobProgress exposes onTickWhileS3Sync callback
- App wires callback to usePaginatedSongs.refresh() to pull fresh song data while sync runs

packages/frontend/src/App.tsx

@@ -128,7 +128,8 @@ const RekordboxReader: React.FC = () => {
     totalDuration,
     loadNextPage,
     searchSongs,
-    searchQuery
+    searchQuery,
+    refresh
   } = usePaginatedSongs({ pageSize: 100, playlistName: currentPlaylist });
 
   // Export library to XML
@@ -660,7 +661,12 @@ const RekordboxReader: React.FC = () => {
       />
 
       {/* Background Job Progress */}
-      <BackgroundJobProgress />
+      <BackgroundJobProgress
+        onTickWhileS3Sync={() => {
+          // Light refresh to pick up newly set hasS3File flags promptly
+          refresh();
+        }}
+      />
     </Box>
   );
 };

packages/frontend/src/components/BackgroundJobProgress.tsx

@@ -45,12 +45,15 @@ interface BackgroundJobProgressProps {
   jobId?: string;
   onJobComplete?: (result: any) => void;
   onJobError?: (error: string) => void;
+  // Called on each polling tick while an S3 sync job is running
+  onTickWhileS3Sync?: () => void;
 }
 
 export const BackgroundJobProgress: React.FC<BackgroundJobProgressProps> = ({
   jobId,
   onJobComplete,
   onJobError,
+  onTickWhileS3Sync,
 }) => {
   const [jobs, setJobs] = useState<JobProgress[]>([]);
   const [loading, setLoading] = useState(false);
@@ -100,7 +103,8 @@ export const BackgroundJobProgress: React.FC<BackgroundJobProgressProps> = ({
 
     intervalRef.current = setInterval(() => {
       // Update all active jobs
-      const activeJobIds = jobs.filter(job => job.status === 'running').map(job => job.jobId);
+      const activeJobs = jobs.filter(job => job.status === 'running');
+      const activeJobIds = activeJobs.map(job => job.jobId);
       activeJobIds.forEach(jobId => {
         updateJobProgress(jobId);
       });
@@ -109,6 +113,11 @@ export const BackgroundJobProgress: React.FC<BackgroundJobProgressProps> = ({
       if (jobId) {
         updateJobProgress(jobId);
       }
+      
+      // Notify consumer while an S3 sync is running (to refresh song list, etc.)
+      if (onTickWhileS3Sync && activeJobs.some(j => j.type === 's3-sync')) {
+        onTickWhileS3Sync();
+      }
     }, 2000); // Poll every 2 seconds for less frequent updates
   };