Merge SpaceFormer demo (viser + CLI + Gradio) under demo/

card: add local viser demo section

License: weights are CC-BY-NC-4.0 (non-commercial); add dataset usage notice; Replica is eval-only

Update README.md

Update README.md

Add SpaceFormer weights (spaceformer_512_siglip2_ssccc) + model card

initial commit