- Add run_dir and checkpoint_frequency to PPOArgs
- Update train.py to use run_dir for SummaryBoard, model saving, and loss plots
- Create configs/production_training.yaml for HPC production runs
- Update HPC.md with run_dir staging strategy details
Match comment style from previous cleanup commit:
- No section divider bars, no echo progress lines, no prose comments
on obvious commands
- Replace XDG_CACHE_HOME with explicit PIP_CACHE_DIR and UV_CACHE_DIR
- Drop MPLCONFIGDIR (matplotlib cache is negligible in size)
- docs/HPC.md: cluster table, setup with vsc-venv, interactive debug
(shell + JupyterLab on donphan), PBS batch submission, dependency mgmt
- README.md: HPC section condensed to a single link to docs/HPC.md