Mistral 3+ / Ministral runner.
Mistral 3 / 3.5 / 4 and Ministral 3 ship as general.architecture = mistral3 or mistral4 in their GGUF converters — Llama-shaped with
per-arch deltas. This crate is a thin wrapper over
[rlx_llama32::Llama32Runner] with arch validation.
Caveat: The underlying rlx-llama32 builder doesn't yet apply
Mistral 3's per-layer sliding-window mask or Mistral-specific RoPE
base — runs will produce some tokens but won't match the upstream
reference until those land in rlx-llama32. PLAN.md M4 follow-up.