fix: add photo_path fields to frontend Item interface to display saved photos

The backend returns photo_path, photo_thumbnail_path, and photo_upload_date
from the AI auto-save feature, but the frontend Item interface was missing
these fields, causing images not to display in ItemDetailModal and InventoryTable.

Updated:
- frontend/lib/db.ts: Added missing photo fields to Item interface
- frontend/components/ItemDetailModal.tsx: Use photo_path first, fallback to image_url
- frontend/components/InventoryTable.tsx: Use photo_path first, fallback to image_url

This ensures the UI can now display photos saved by the auto-photo-save feature.

frontend/components/ItemDetailModal.tsx

@@ -22,7 +22,11 @@ export default function ItemDetailModal({
 }: ItemDetailModalProps) {
   const [showPhotoUpload, setShowPhotoUpload] = useState(false);
   const [currentPhoto, setCurrentPhoto] = useState<{ thumbnail_url: string; full_url: string } | null>(
-    item.image_url ? { thumbnail_url: item.image_url, full_url: item.image_url } : null
+    item.photo_path && item.photo_thumbnail_path
+      ? { thumbnail_url: item.photo_thumbnail_path, full_url: item.photo_path }
+      : item.image_url
+        ? { thumbnail_url: item.image_url, full_url: item.image_url }
+        : null
   );
   const [isDeleting, setIsDeleting] = useState(false);
   const photoUploadRef = useRef<HTMLDivElement>(null);