[v2.15.0] - pending cut

Post-v2.14.0 work on main plus maintainer release-process hardening, consolidated here for the next semver (supersede incomplete multi-channel 2.14.0 per Release workflow §5 rather than re-tagging). Run cog bump --version 2.15.0 only after pre-release gates pass; this page is authored before the version chore so the cut is not blocked on writing notes.

Highlights: runtime-loaded Fortran potentials (potentials_path / dlopen), process-search fixed-atom restore, per-image LAMMPS MPI isolation, MPI C API build path, and the full release/PyPI/feedstock/Nickel GHA process.

Release notes