Zero-crop photo panels: object-fit cover hides Ken Burns cropping

When a user says no person may be cropped out of family or group photos, use exact-aspect panels: justified rows where each panel w/h equals the photo aspect, then scale rows to fit and centre them, so object-fit:cover never trims anything. Face-detection checks are not enough, because they miss people at the image edges. Also remove any slow zoom inside the frame (transform: scale up to 1.05): it gradually crops the edges and undoes the zero-crop layout. Preview stills must avoid transition frames such as page slides and lens wipes, or the preview looks cropped when the layout is fine.