Mistral medium 3.5 128B, MLX 4bit, ~70 GB

I converted Mistral medium 3.5 128B to MLX 4bit. Eagle model for speculative decoding is not yet supported by MLX. Vision encoder included (full BF16 unquantized. Thinking mode works (reasoning_effort="high" gives you the [THINK]...[/THINK] chain), tool calling works, 256K context. There was a bug in mlx-vlm's mistral3 sanitize function: it wasn't stripping the model. prefix from vision tower and projector keys. This caused 438 parameters to be skipped. I patched it locally before converting.