recipe: no horizontal flip and full-resolution masks by default (winner of the 2026-09-28/29 comparison)

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

README.md

@@ -297,7 +297,7 @@ python tools/ledger.py show            # the table; `render` writes runs/README.
 sbatch slurm/train.sbatch 2026-10-02_alc
 ```
 
-`tools/train_run.py` trains with the recipe from `src/training/train_yolo_seg.py`,
+`tools/train_run.py` trains with the recipe from `src/training/train_yolo_seg.py` (since 2026-09-29 with no horizontal flip and full-resolution masks, the settings that won the comparison on unseen gold frames; any setting can be overridden with `--set KEY=VALUE`),
 copies `best.pt` to `models/registry/<family>-seg-<tag>-<date>/weights.pt` (LFS) with
 `metadata.json`, measures the weights on `data/gold/` with the studio's evaluation
 code (`src/eval/`, vendored), and gates against the active model's