Function test_dense_fixture 

pub fn test_dense_fixture() -> ModelConfig

Matches the generated on-disk fixture exactly (hidden_dim, head counts, ffn_dim, vocab, rope_theta, eps). Used by ferrox inspect-run and the cross-validation test in crates/ferrox-models/tests/gguf_roundtrip.rs to prove the real GGUF loader + forward pass produce the same numbers as an independent NumPy reference implementation reading the same file.