Title: Delay in Image Visibility After Adding Folder

Description:
When adding a folder with a large number of images (around 200), it takes approximately 8 seconds before the images appear on the home tab.

This delay seems to occur because:

The backend performs all thumbnail generation and database insertion in a single blocking process before returning.

The frontend only triggers a refetch after the entire process completes — meaning no intermediate updates are shown.

As a result, the user perceives a long pause before new images appear.

Steps to Reproduce:

- Add a folder containing ~200 images.

- Observe that the images take several seconds to appear on the home tab.

Expected Behavior:
- The images should appear incrementally or much faster, even for large folders.