refactor: update QuestMap component to use new node structure and simplify DAG class

app/src/components/QuestMap.vue

@@ -69,14 +69,14 @@ async function computeGraphData() {
     const nodesValues = dag.getNodes()
 
     const nodes = nodesValues.map((node) => ({
-      id: node._id,
+      id: node.id,
       title: node.title,
       x: marginX * node.layer * 2,
       y:
         marginY * node.index -
-        (marginX * dag.getLayer(node._id)) / 2 +
+        (marginX * dag.getLayer(node.id)) / 2 +
         svgHeight.value / 2,
-      completed: store.progress[node._id]?.completed || false,
+      completed: store.progress[node.id]?.completed || false,
       unlocked: node.requirements.every(
         (req: string) => store.progress[req]?.completed
       ),