P: Allow AI Mask Sync to Run in the Background

Currently, when syncing AI masks across multiple photos, a modal progress window appears that blocks the entire application — even if I want to work on other photos that are not being processed, I can’t.

It would be very helpful if this process could run in the background: the photos being processed could remain temporarily locked, but users should still be able to browse and edit other images in their catalog.

This behavior already exists for other operations like export or preview generation, and it greatly improves workflow efficiency.