docs(training-run): record 2026-06-02 first-GNN-run results (#222)

3hr wall-clock. Lean 16 epochs early-stop, coq 17 epochs early-stop.
Best MRR 0.92 (epoch 9 coq, val_loss 1.01). Best val_loss 0.98 (epoch 12
coq, MRR 0.79). 6 checkpoints + best_model + final_model + gnn_ranker
(162MB production-deployable) saved. Total artefact footprint 952MB.

Surfaced issues (separately tracked): BSON UndefVarError at final-save
path (non-fatal; checkpoint scaffold rescued); launcher pointed ingest
at empty training_data/ dirs (JSONL fallback rescued); per-epoch metrics
CSV overwritten between provers (lean lost).

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath