fix: ruff lint fixes for v3 test files

tests/test_pbt_v3_posterior.py

@@ -16,12 +16,12 @@ from hypothesis import strategies as st
 
 from services.aggregation.bayesian import V3Posterior, compute_v3_posterior
 from services.aggregation.regime import (
-    V3RegimeClassification,
     MarketRegime,
+    V3RegimeClassification,
     classify_regime_v3,
 )
-from services.aggregation.worker import EvidenceCluster
 from services.aggregation.scoring import EvidenceUnit
+from services.aggregation.worker import EvidenceCluster
 
 # ---------------------------------------------------------------------------
 # Hypothesis strategies
@@ -459,7 +459,8 @@ def test_property_10_suppression_by_weak_dimension(
 # Feature: math-core-v3-engine
 # ---------------------------------------------------------------------------
 
-from datetime import datetime, timezone as _tz
+from datetime import datetime
+from datetime import timezone as _tz
 
 # Strategies for Property 17
 extraction_failure_rates = st.floats(