feat: node creation and serialization logic in workflow editor

src/js/workflow/nodes/base-node.ts

@@ -9,6 +9,7 @@ export abstract class BaseWorkflowNode extends ClassicPreset.Node {
   width = 280;
   height = 140;
   execStatus: 'idle' | 'running' | 'completed' | 'error' = 'idle';
+  nodeType: string = '';
 
   constructor(label: string) {
     super(label);

src/js/workflow/nodes/registry.ts

@@ -593,7 +593,9 @@ export const nodeRegistry: Record<string, NodeRegistryEntry> = {
 export function createNodeByType(type: string): BaseWorkflowNode | null {
   const entry = nodeRegistry[type];
   if (!entry) return null;
-  return entry.factory();
+  const node = entry.factory();
+  node.nodeType = type;
+  return node;
 }
 
 export function getNodesByCategory(): Record<