Fix unneeded image processing

backend/src/main/java/com/storycove/controller/StoryController.java

@@ -178,8 +178,9 @@ public class StoryController {
 
         Story updatedStory = storyService.updateWithTagNames(id, request);
 
-        // Process external images in content after saving
-        updatedStory = processExternalImagesIfNeeded(updatedStory);
+        // Image processing for updates is handled by the frontend via the dedicated
+        // /process-content-images endpoint, so no async processing is triggered here.
+        // (Async processing on every PUT caused concurrent duplicate downloads.)
 
         logger.info("Successfully updated story: {}", updatedStory.getTitle());
         return ResponseEntity.ok(convertToDto(updatedStory));