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/hunt/program.py

@@ -67,7 +67,8 @@ def signature_for(mask: Iterable[str] = ()) -> type[dspy.Signature]:
             continue
         fields[name] = (str, dspy.InputField(desc=desc))
     fields["findings"] = (list[Finding], dspy.OutputField(desc="JSON list; empty when the change is ordinary"))
-    return dspy.Signature(fields, BASELINE_INSTRUCTION)
+    signature: type[dspy.Signature] = dspy.Signature(fields, BASELINE_INSTRUCTION)
+    return signature
 
 
 def numbered(lines: Sequence[str], start: int, end: int) -> str:
@@ -194,7 +195,9 @@ class _Loop(dspy.ReAct):
 
     loop_parse_failed = False
 
-    def _call_with_potential_trajectory_truncation(self, module, trajectory, **input_args):
+    def _call_with_potential_trajectory_truncation(
+        self, module: dspy.Module, trajectory: dict[str, Any], **input_args: str
+    ) -> dspy.Prediction:
         try:
             return super()._call_with_potential_trajectory_truncation(module, trajectory, **input_args)
         except dspy.utils.exceptions.AdapterParseError as error: