fix(verifier): resolve CodeQL no-effect Protocol stub

VerifierStrategy.verify used `...` as its body, which CodeQL flags as
py/ineffectual-statement and which also diverged from the existing
FindingVerifier Protocol house style. Use a docstring body instead, and
drop the now-redundant quoted forward reference (UP037, future annotations).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: pureliture

src/security_scanner/core/evaluation/verifier_harness.py

@@ -42,7 +42,8 @@
 class VerifierStrategy(Protocol):
     """Structural type for a candidate-to-result verifier strategy."""
 
-    def verify(self, finding: Finding) -> VerifierResult: ...
+    def verify(self, finding: Finding) -> VerifierResult:
+        """Return a verifier result for one finding."""
 
 
 @dataclass(frozen=True)
@@ -83,7 +84,7 @@ def verify(self, finding: Finding) -> VerifierResult:
     @classmethod
     def from_file(
         cls, path: str | Path, *, min_confidence: float = 0.60
-    ) -> "RecordedVerifierStrategy":
+    ) -> RecordedVerifierStrategy:
         data = json.loads(Path(path).read_text(encoding="utf-8"))
         if not isinstance(data, Mapping):
             raise ValueError("Recorded responses file must contain a JSON object.")