ketos 7 defaults to safetensors output, but kraken's load_any() only
handles CoreML (.mlmodel). Adding --weights-format coreml ensures the
hot-swap after training produces a file that load_any() can parse.
Also fixed _find_best_model to look for best_<score>.mlmodel (produced
by --weights-format coreml) in addition to the previous checkpoint_*
pattern.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>