feat: Update policy simulation metrics and tests to align with new naming conventions and enhance telemetry coverage

src/Scheduler/StellaOps.Scheduler.WebService/PolicySimulations/PolicySimulationMetricsProvider.cs

@@ -56,7 +56,7 @@ internal sealed class PolicySimulationMetricsProvider : IPolicySimulationMetrics
             unit: "runs",
             description: "Queued policy simulation jobs grouped by status.");
         _latencyHistogram = _meter.CreateHistogram<double>(
-            "policy_simulation_latency",
+            "policy_simulation_latency_seconds",
             unit: "s",
             description: "End-to-end policy simulation latency (seconds).");
     }