refactor: extract train_config.py + run_artifacts.py from train.py; slim results scripts

Cleanup by a prior agent, verified green here: 'just smoke' (erase arm)
runs end-to-end and all four wired gates pass (verify_rewards 52/52,
verify_eval_gap, verify_partition, verify_science_invariants).

- train.py -318 lines: Config dataclass -> train_config.py, checkpoint/
  deploy-artifact IO -> run_artifacts.py.
- results.py / results_deploy.py / probe_distill.py slimmed.
- drop stale derived csvs under out/figs (a5_generalisation, dyn_*,
  substrate_aggregate, train_vs_deploy_60).
- gitignore /.pi/ panel scratch.

Co-Authored-By: Claudypoo <288921227+claudypoo@users.noreply.github.com>

.gitignore

@@ -28,3 +28,5 @@ __pycache__/
 .pytest_cache/
 .ruff_cache/
 .mypy_cache/
+# pi/pueue panel scratch
+/.pi/