Add explicit licenses for pretrained models

[chandrasekarnarayana]

Hello everyone,

It would be very helpful if each pretrained model in this repository included explicit licensing information.

Currently, it is difficult to determine:

commercial usage rights,
redistribution permissions,
dataset provenance,
and whether trained weights inherit dataset restrictions.

Adding a small license section (or SPDX metadata) per model/checkpoint would greatly improve reproducibility, deployment, and industrial adoption.

For example:

Code license
Dataset license
Model/checkpoint license
Commercial use allowed: Yes/No

Thanks again for the great work and for supporting the bioimage community.