Update GitHub URL to UVA-Computer-Vision-Lab/sab-3r

Bump Gradio SDK to 5.33.0 (gradio 4.44.1 imports HfFolder which is gone from huggingface_hub>=1.0)

Reorganize: demo lives in demo/ in the GitHub repo; at Space root we keep app.py+demo.py next to mast3r/ and dust3r/

Initial SAB3R demo release

initial commit