Add elevateNodesOnSelect prop, fix z-index not increased when selecting nodes

packages/svelte/src/lib/container/SvelteFlow/Wrapper.svelte

@@ -64,6 +64,7 @@
     colorModeSSR,
     style,
     defaultEdgeOptions,
+    elevateNodesOnSelect,
     ...divAttributes
   } = $derived(rest);
 

packages/svelte/src/lib/container/SvelteFlow/types.ts

@@ -328,6 +328,11 @@ export type SvelteFlowProps = NodeEvents &
      * If you have custom connection logic its preferred to use this callback over the isValidConnection prop on the handle component for performance reasons.
      * @default (connection: Connection) => true
      */
+
+    /** Enabling this option will raise the z-index of nodes when they are selected.
+     * @default true
+     */
+    elevateNodesOnSelect?: boolean;
     isValidConnection?: IsValidConnection;
     /** This event handler is called when the user begins to pan or zoom the viewport */
     onMoveStart?: OnMoveStart;

packages/svelte/src/lib/store/initial-store.svelte.ts

@@ -82,7 +82,7 @@ export const getInitialStore = (signals: StoreSignals) => {
       adoptUserNodes(signals.nodes, this.nodeLookup, this.parentLookup, {
         nodeExtent: this.nodeExtent,
         nodeOrigin: this.nodeOrigin,
-        elevateNodesOnSelect: false,
+        elevateNodesOnSelect: signals.props.elevateNodesOnSelect ?? true,
         checkEquality: true
       });
       return signals.nodes;