Unify Samila's snapshot I/O so callers can move generated data and reproducible configs between files…

Unify Samila's snapshot I/O so callers can move generated data and reproducible configs between files…: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). The public GenerativeImage(data=...) and GenerativeImage(config=...) inputs must each accept a…