Slurm assumptions undocumented for training and evaluation scripts

[anselmotalotta]

• training/resume_h100.py and evaluation/run_hle.py fail on non-Slurm hosts (squeue/sbatch errors).
• README doesn’t state these scripts require a Slurm cluster, Slurm client binaries, and valid slurm.conf.
• Fix request: document prerequisites or provide a local/manual mode with clear instructions.

[shizhediao]

At the moment, our script only supports the Slurm environment, and we haven’t tested it in local mode. We’ll update the README to reflect this.