add: pre/post eval + summarize + bumped GRPO config (training/summarize.py)

add: pre/post eval + summarize + bumped GRPO config (training/evaluate.py)

fix: multi-GPU SFT shape mismatch (training/sft_warmstart.py)

fix: refresh env._latent after step loop in oracle collector

fix: accept --difficulty in sft_warmstart to match space/training/app.py

fix: include requirements-train.txt + tests (glob bug)