chore: merge the rest of the nodes back into this structure, and make sure that start and end nodes are not deletable.

src/pages/VisProgPage/visualProgrammingUI/nodes/StartNode.tsx

@@ -20,7 +20,7 @@ export type StartNode = Node<StartNodeData>
 export default function StartNode(props: NodeProps<Node>) {
   return (
     <>
-      <Toolbar nodeId={props.id} allowDelete={true}/>
+      <Toolbar nodeId={props.id} allowDelete={false}/>
       <div className={`${styles.defaultNode} ${styles.nodeStart}`}>
         <div className={"flex-row gap-sm"}>
           Start