phase-6: 50-problem pool, baseline rollout harness for HF Jobs

phase-5 cleanup: episode_id in metadata, openenv push doc, README install line, psutil dev dep

phase-4: ShutdownGymClient with EnvClient hooks + integration tests

phase-3: ShutdownGymEnvironment + server stack; fix audit.py to preserve scalar types in sanitize_args

phase-1: implement primitives (models, sandbox, restricted_python, audit, timer) + tests

chore: pin python 3.12, rebuild venv, rename master→main

Initial scaffold: CLAUDE.md, .claude/ structure, language scaffold, pre-commit hook