fix(types): mypy clean again over src; stub-less libraries and the benchmark imports handled in pyproject

66 errors had accumulated in src since the last green run (the hunt modules of groups 4-6, stats, candidates,
runner). Codex typed them without behaviour change; the 17 inline import-untyped ignores it added are replaced by
one override for dspy, pandas, statsmodels and scikit-learn, and the hunt package's lazy imports of benchmarks/
(never type-checked, not in files) are followed silently so src stays strict against their signatures.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

src/openultrasast/stats.py

@@ -167,7 +167,7 @@ def separation(frame: Any, label: str, columns: Iterable[str]) -> Any:
     import pandas as pd
     from sklearn.metrics import roc_auc_score
 
-    rows = []
+    rows: list[dict[str, str | float | None]] = []
     labelled = frame[frame[label].isin([0, 1])]
     for column in columns:
         series = pd.to_numeric(labelled[column], errors="coerce") if column in labelled else None