Refactor NavigationState

The `remember` block creating the `NavigationState` is now keyed with `startRoute` and `topLevelRoutes`. This ensures the state is correctly recalculated when these parameters change. Additionally, the `rememberSerializable` call for `topLevelRoute` includes these keys for better state consistency.

Author: dturner

app/src/main/java/com/example/nav3recipes/multiplestacks/NavigationState.kt

@@ -44,14 +44,15 @@ fun rememberNavigationState(
 ): NavigationState {
 
     val topLevelRoute = rememberSerializable(
+        startRoute, topLevelRoutes,
         serializer = MutableStateSerializer(NavKeySerializer())
     ) {
         mutableStateOf(startRoute)
     }
 
     val backStacks = topLevelRoutes.associateWith { key -> rememberNavBackStack(key) }
 
-    return remember {
+    return remember(startRoute, topLevelRoutes) {
         NavigationState(
             startRoute = startRoute,
             topLevelRoute = topLevelRoute,