Rename 'total' to 'train_loss' in train.csv

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/training/train_gtauav.py

@@ -754,6 +754,8 @@ def train(cfg: TrainConfigGTAUAV) -> None:
 
         # Log train metrics to CSV (includes recall/AP if eval ran this epoch).
         train_row = {**means}
+        if "total" in train_row:
+            train_row["train_loss"] = train_row.pop("total")
         if train_recall:
             train_row["r@1_q2g"] = train_recall.get("r@1_q2g", 0.0)
             train_row["r@5_q2g"] = train_recall.get("r@5_q2g", 0.0)