fix(rectification): close round A/2 tail gaps in tests, CI, and stale-score reuse

Window_scan assertions now match the public from_sign/to_sign contract, the
staging quick gate runs the rectification Python suite, and compare-candidates
rescores when stored policy lags the live engine identity.

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/rectification/api_service.py

@@ -152,6 +152,15 @@ def _rectification_report(
     }
 
 
+def engine_scoring_versions() -> dict[str, str]:
+    """Identity fields also returned by `/api/rectification/v5/score`, without scoring."""
+    return {
+        "algorithm_version": ALGORITHM_VERSION,
+        "event_contract_version": EVENT_CONTRACT_VERSION,
+        "decision_policy_version": POLICY_VERSION,
+    }
+
+
 def candidate_features(request: RectificationRequest) -> dict[str, Any]:
     spec = calculation_spec(request)
     spec_hash = sha256(spec)