PERMANENCE: reversibility-aware RL environment for training LLM agents

Run 6.1: env precondition fix (destructive DB ops on missing tables short-circuit)

Run 6: forced variants (eps 50%→70%), β_rank=0.25, R-level bonus, μ=2 PPO epochs, balanced R1-R5 warmup traces

Run 4: tech-only curriculum, 3B model, integrated deploy task

Run 4: tech-only curriculum, 3B model, integrated deploy task