Some models like unsloth/Qwen3-0.6B have no safetensors metadata
on Hugging Face, so the training model selector showed no parameter
size badge. The chat model picker already had extractParamLabel()
as a fallback that parses sizes like "0.6B" from the model name.
Add the same fallback to the training model selector and the
onboarding model selection step.
Co-authored-by: Daniel Han <danielhanchen@users.noreply.github.com>