Weight licenses that add dataset-derived non-commercial terms #923

Policy: weights keep the license their authors declare. Some 1.6.0 code, notices and HF cards still add dataset-derived non-commercial terms instead:

• PP-LiteSeg and ViTMatte (code notices and HF cards), FCOS3D (code notices).
• weights/convert_gtr_sem_weights.py stamps PP-LiteSeg's Cityscapes non-commercial license into LibreGTR*-sem.pt metadata, while GTR upstream declares MIT.
• DetAny3D: the changelog says CC-BY-NC-4.0, the website registry says no license was declared, licensing.md says "restrictive weight terms".

Needs a maintainer decision per model; U-Net was already moved to its upstream Apache-2.0 in #908.