perf: efekt suruklemesinde kitlenme fix (kare hizi throttle, repaint izolasyonu, downsampling, cache sinirlari), .deb guncellendi

lib/services/image_manager.dart

@@ -63,6 +63,9 @@ class ImageManager extends ChangeNotifier {
           .indexWhere((p) => p.split(Platform.pathSeparator).last == base);
     }
     if (_currentIndex < 0) _currentIndex = 0;
+
+    // Eski klasörün decode edilmiş görsellerini bırak; canlı görsel korunur
+    PaintingBinding.instance.imageCache.clear();
     notifyListeners();
   }
 
@@ -86,8 +89,8 @@ class ImageManager extends ChangeNotifier {
 
   /// Configure image cache for high-res images
   static void configureCache() {
-    PaintingBinding.instance.imageCache.maximumSize = 1000;
-    PaintingBinding.instance.imageCache.maximumSizeBytes = 1024 * 1024 * 1024; // 1 GB
+    PaintingBinding.instance.imageCache.maximumSize = 16;
+    PaintingBinding.instance.imageCache.maximumSizeBytes = 256 * 1024 * 1024; // 256 MB
   }
 
   void clear() {