feat: new projects start with empty state

frontend/src/app/canvas/CanvasPage.tsx

@@ -137,6 +137,7 @@ function getInitialGraph(projectId: string | undefined): { nodes: AppNode[]; edg
     if (stored && (stored.nodes.length > 0 || stored.edges.length > 0)) {
       return { nodes: stored.nodes as AppNode[], edges: stored.edges as AppEdge[] }
     }
+    return { nodes: [], edges: [] }
   }
   return getExampleGraph()
 }