chore(vulture): whitelist DecisionPolicy + ResolveSigner

Both are imported under TYPE_CHECKING and used inside cast("...") string
literals, which vulture can't trace. Mirrors the existing pattern in
vulture_whitelist.py for other false-positive type imports.

Author: vvillait88

vulture_whitelist.py

@@ -20,3 +20,7 @@
 ScoreDetail  # noqa: F821
 ScoreStatus  # noqa: F821
 OperatorVerification  # noqa: F821
+
+# TYPE_CHECKING imports referenced inside string-literal cast() calls
+DecisionPolicy  # noqa: F821
+ResolveSigner  # noqa: F821