perf: type-aware image memory cache bounds

lib/screens/libraries/tabs/library_browse_tab.dart

@@ -1299,6 +1299,7 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<PlexMetadata, LibraryBr
       final (_, memHeight) = PlexImageHelper.getMemCacheDimensions(
         displayWidth: scaledWidth.isFinite && scaledWidth > 0 ? scaledWidth.round() : 0,
         displayHeight: scaledHeight.isFinite && scaledHeight > 0 ? scaledHeight.round() : 0,
+        imageType: ImageType.poster,
       );
 
       precacheImage(

lib/utils/plex_image_helper.dart

@@ -198,16 +198,29 @@ class PlexImageHelper {
     }
   }
 
-  /// Generates cache-friendly dimensions for memory caching
+  /// Generates cache-friendly dimensions for memory caching.
+  ///
+  /// Max bounds are type-aware so large originals (e.g. failed server
+  /// transcodes or external EPG images) are capped at a resolution
+  /// appropriate for the display context.
   static (int memWidth, int memHeight) getMemCacheDimensions({
     required int displayWidth,
     required int displayHeight,
     double scaleFactor = 1.0,
+    ImageType imageType = ImageType.poster,
   }) {
     final scaledWidth = (displayWidth * scaleFactor).round();
     final scaledHeight = (displayHeight * scaleFactor).round();
 
-    return (scaledWidth.clamp(120, 1200), scaledHeight.clamp(180, 1800));
+    final (int maxW, int maxH) = switch (imageType) {
+      ImageType.poster => (720, 1080),
+      ImageType.thumb => (960, 540),
+      ImageType.art => (1920, 1080),
+      ImageType.logo => (600, 300),
+      ImageType.avatar => (300, 300),
+    };
+
+    return (scaledWidth.clamp(120, maxW), scaledHeight.clamp(180, maxH));
   }
 
   /// Determines if an image path is suitable for transcoding

lib/widgets/plex_optimized_image.dart

@@ -329,6 +329,7 @@ class PlexOptimizedImage extends StatelessWidget {
     final (memWidth, memHeight) = PlexImageHelper.getMemCacheDimensions(
       displayWidth: scaledWidth.isFinite && scaledWidth > 0 ? scaledWidth.round() : 0,
       displayHeight: scaledHeight.isFinite && scaledHeight > 0 ? scaledHeight.round() : 0,
+      imageType: imageType,
     );
 
     // Generate cache key if not provided