Three issues fixed:
1. --resize both was removed in ketos 7; replaced with --resize union
which extends the model's class mapping to include training data classes.
2. ketos ignores -s when -i is present, so the 1800px blla model caused
7+ GB peak RAM and OOM-killed the host (no swap, 5 GB free).
Now checks the loaded model's input height: only uses the base model
when it was already fine-tuned at 800px; otherwise trains from scratch
at 800px (~200 MB peak). After the first run the trained 800px model
becomes the base for all subsequent fine-tuning runs.
3. segtrain now computes and returns cer = 1 - accuracy, matching the
recognition training path.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>