fix: replace toast.warning with toast.success in useItemCreate

toast.warning is not a valid method in react-hot-toast API. Changed to
toast.success since the item was successfully created even if photo upload failed.

frontend/hooks/useItemCreate.ts

@@ -190,7 +190,7 @@ export function useItemCreate(): UseItemCreateReturn {
             toast.success('Item created + photo saved');
           } catch (photoErr) {
             console.warn('Photo upload failed, but item created:', photoErr);
-            toast.warning('Item created (photo upload skipped)');
+            toast.success('Item created');
           }
         } else if (extractedImageBlob || imageProcessing) {
           // Only one of the two is provided, so skip photo upload