About initial root translation 

Thanks for your wonder work,

I am quite confused about why we use init root translation from [this](https://github.com/vye16/slahmr/blob/main/slahmr/preproc/export_phalp.py#L116)  instead of  predicted from HMR model (eg. HMR2.0)


Could you help me understand more about this step?

