Restore 8acfc94e for impact-reg-konfai 1.8.6

Give each layer its receptive field in models.json, and keep one DINOv2 model

Let the 2D DINOv2 and SAM 2.1 models take slices of any size

Add the anatomix ViT encoder, trace both anatomix networks in evaluation mode

Expand models.json to all 30 models (per-directory FOV/dim/channels)

Add models.json registry: per-model intrinsics (dimension, channels, field-of-view) for IMPACT registration presets