Add privacy-audited MFI methane extended evaluation GCMC

Add three MFI methane 20k-step model releases

Rebuild MFI methane v2 after dropping corrupt RASPA movie frames

Rename lj_feasst_morph_scale_mu_grid_v1/ to lj_feasst_mu_grid_v1/

Add FEASST LJ morph-scale mu-grid train/val archives

Add FEASST LJ small-v1 train/val/test archives

Update mfi_methane_v1/README.md

Update mfi_methane_v2/README.md

Point v2 README at mfi_methane_v1/

Rename mfi_methane/ to mfi_methane_v1/

Add MFI methane GCMC v2 collection beside v1

Add sanitized ideal-gas benchmark datasets

Add sanitized MFI methane GCMC benchmark

initial commit