fix: revert to tabpfn v2, add TABPFN_TOKEN support, and update v2 API usage

fix: downgrade tabpfn to 0.1.11, class-level weight cache, fix ravel on list

fix: pre-accept TabPFN license in Dockerfile ENV + cache file + all env var names

fix: add missing scipy dep, TabPFN weight caching, better error logging

Initial deployment of ModelMatrix-HF