F(backend): add public media derivatives pipeline

apps/gallery/tasks.py

@@ -1,20 +1,26 @@
-from celery import shared_task
-from PIL import Image
 import logging
 
+from celery import shared_task
+
+from core.media import safe_process_public_image
+
 logger = logging.getLogger(__name__)
 
 @shared_task
 def process_uploaded_image(gallery_id):
-    """Process uploaded image: compress, resize, extract metadata"""
+    """Process gallery image derivatives and refresh metadata."""
     try:
         from .models import Gallery
         gallery_item = Gallery.objects.get(id=gallery_id)
         
         if gallery_item.image:
-            # This will trigger the compression and metadata extraction
-            gallery_item.compress_image()
-            
+            result = safe_process_public_image(gallery_item.image, "gallery", force=True)
+            if result:
+                Gallery.objects.filter(pk=gallery_item.pk).update(
+                    file_size=result.file_size,
+                    width=result.width,
+                    height=result.height,
+                )
             logger.info(f"Processed image: {gallery_item.title}")
             return f"Processed image: {gallery_item.title}"