Restore checkpoints/{era5,hres}_best.pt (server-side copy from b2ac1e4)

Reorganize bundled assets into checkpoints/ and data/ folders

README: add Mosaic mosaic-tile header banner

Add Mosaic header banner figure

README: reorder bottom sections; drop Field/Value header

README: move Citation to the very end

README: keep YAML frontmatter on HF; align body with GitHub

Add 'Getting the weights' note; align with GitHub mirror

Bundle norm_stats and static_vars npz assets

Initial release: Mosaic weather model (era5 + hres variants)

initial commit