test(ltl): pin that a slow policy does not fail on time alone

Same 300-observation trace at two cadences: a 300 second bound holds for the
seeded arm and violates for the model arm eight observations before the
predicate fires, while a step bound holds for both. Green before and after,
because the step unit already worked; this pins the property rather than
fixing it.

Claude-Session: https://claude.ai/code/session_01A5KmftdEJ49A9z5mF5ESrX

internal/ltl/evaluator_test.go

@@ -153,5 +153,5 @@ func TestObserve_PanicsOnUnknownFormulaType(t *testing.T) {
 			t.Errorf("expected panic on unsupported formula type")
 		}
 	}()
-	reduce(unsupportedFormula{}, time.Now())
+	reduce(unsupportedFormula{}, time.Now(), 1)
 }