feat(node): add as property to allow custom HTML elements

packages/system/src/types/nodes.ts

@@ -23,6 +23,10 @@ export type NodeBase<
   data: NodeData;
   /** Type of node defined in `nodeTypes`. */
   type?: NodeType;
+  /** Custom element type for rendering the node (e.g., 'div', 'li', etc.).
+   * @default 'div'
+   */
+  as?: Extract<keyof HTMLElementTagNameMap, 'div' | 'li' | 'ul' | 'ol'>;
   /**
    * Only relevant for default, source, target nodeType. Controls source position.
    * @example 'right', 'left', 'top', 'bottom'