Add tests for V3

[bejaeger]

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[gemini-code-assist]

Code Review

This pull request updates the default model version to V3 and standardizes the embedding dimension variable by renaming ninp to emsize across the architecture definitions and test suites. It introduces a new embedding_dim property to the architecture interface and refactors the architecture name resolution to use explicit class instance checks. Furthermore, the PR modifies model loading and saving logic to accommodate V3 checkpoints, specifically by stripping criterion keys and including inference configurations, while temporarily disabling SVD on GPU and HuggingFace license checks. I have no feedback to provide.

[brendan-priorlabs]

@bejaeger, in order to keep everything (client->server->fomo-fitting->TabPFN) compatible I have re-uploaded the checkpoints with the naming scheme used in 2.5 and 2.6. Highly suggest you cherry-pick in this commit: 92a1fd9 (We're serving off-of a branch that is essentially your PR here + that commit.)