Replace Python numerical kernels with native C execution

frontend/src/SimulationResultsView.tsx

@@ -146,12 +146,12 @@ type ResultPayload = {
         stateTransitionTimes?: number[];
       }>;
     };
-    pressureFlow: {
+    pressureFlow?: {
       solveCount: number;
       maxScaledResidual: number;
       maxEvaluationsPerSolve: number;
     };
-    stream: {
+    stream?: {
       maxIterationsPerSolve: number;
     };
     stateCount: number;