Add OpenCS2 favicon set (32/192/512 PNG, transparent corners)

Add OpenCS2 banner header below abstract + social preview images

Update URLs after rename: HF Space + GitHub repo → opencs2

Nerfies-style home, paper-style match header, prettier setup, dataset README

Cut first-paint payload: per-icon phosphor imports + WebP radars + non-sticky header

Initial CS2 render dataset viewer