perf(downloads): reuse HTTP connections between tracks

lib/providers/download_queue_provider.dart

@@ -320,7 +320,6 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
   final QueueProcessingGate _queueProcessingGate = QueueProcessingGate();
   StreamSubscription<List<ConnectivityResult>>? _connectivitySub;
   int _downloadCount = 0;
-  static const _cleanupInterval = 50;
   static const _progressPollingInterval = Duration(milliseconds: 1200);
   static const _idleProgressPollEveryTicks = 3;
   static const _progressStreamBootstrapTimeout = Duration(seconds: 3);
@@ -1897,17 +1896,18 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
       await PlatformBridge.endBackgroundDownloadTask();
     }
 
-    if (_downloadCount > 0) {
-      _log.d('Final connection cleanup...');
+    if (stoppedWhilePaused && _downloadCount > 0) {
       try {
         await PlatformBridge.cleanupConnections();
       } catch (e) {
         _log.e('Final cleanup failed: $e');
       }
-      _downloadCount = 0;
     }
+    _downloadCount = 0;
 
     if (!stoppedWhilePaused) {
+      // Releasing idle runtimes already recycles the Rust HTTP pool. A
+      // separate cleanup immediately beforehand only builds it twice.
       await PlatformBridge.releaseNativeMemory();
     }
 

lib/providers/download_queue_provider_single_item.dart

@@ -251,16 +251,9 @@ class _DownloadRun {
       }
 
       n._downloadCount++;
-      if (n._downloadCount % DownloadQueueNotifier._cleanupInterval == 0) {
-        _log.d(
-          'Cleaning up idle connections (after ${n._downloadCount} downloads)...',
-        );
-        try {
-          await PlatformBridge.cleanupConnections();
-        } catch (e) {
-          _log.e('Connection cleanup failed: $e');
-        }
-      }
+      // The HTTP pool expires idle connections itself. Keep warm connections
+      // for the next track; network changes/errors and queue teardown still
+      // recycle the pool when needed.
     } catch (e, stackTrace) {
       await _handleRunException(e, stackTrace);
     } finally {