refactor(examples): switch examples from cra to nextjs

examples/nextjs/pages/DragHandle/DragHandleNode.tsx

@@ -0,0 +1,41 @@
+import React, { memo, FC } from 'react';
+
+import {
+  Handle,
+  Position,
+  NodeProps,
+  Connection,
+  Edge,
+} from '@react-flow/core';
+
+const onConnect = (params: Connection | Edge) =>
+  console.log('handle onConnect', params);
+
+const labelStyle = {
+  display: 'flex',
+  alignItems: 'center',
+};
+
+const dragHandleStyle = {
+  display: 'inline-block',
+  width: 25,
+  height: 25,
+  backgroundColor: 'teal',
+  marginLeft: 5,
+  borderRadius: '50%',
+};
+
+const ColorSelectorNode: FC<NodeProps> = () => {
+  return (
+    <>
+      <Handle type='target' position={Position.Left} onConnect={onConnect} />
+      <div style={labelStyle}>
+        Only draggable here →{' '}
+        <span className='custom-drag-handle' style={dragHandleStyle} />
+      </div>
+      <Handle type='source' position={Position.Right} />
+    </>
+  );
+};
+
+export default memo(ColorSelectorNode);

examples/nextjs/pages/DragHandle/index.tsx

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+import React, { MouseEvent } from 'react';
+import ReactFlow, {
+  Node,
+  Edge,
+  useNodesState,
+  useEdgesState,
+} from '@react-flow/core';
+
+import DragHandleNode from './DragHandleNode';
+
+const nodeTypes = {
+  dragHandleNode: DragHandleNode,
+};
+
+const initialNodes: Node[] = [
+  {
+    id: '2',
+    type: 'dragHandleNode',
+    dragHandle: '.custom-drag-handle',
+    style: { border: '1px solid #ddd', padding: '20px 40px' },
+    position: { x: 200, y: 200 },
+    data: null,
+  },
+];
+
+const onNodeClick = (_: MouseEvent, node: Node) => console.log('click', node);
+
+const initialEdges: Edge[] = [];
+
+const DragHandleFlow = () => {
+  const [nodes, , onNodesChange] = useNodesState(initialNodes);
+  const [edges] = useEdgesState(initialEdges);
+
+  return (
+    <ReactFlow
+      nodes={nodes}
+      onNodesChange={onNodesChange}
+      edges={edges}
+      nodeTypes={nodeTypes}
+      onNodeClick={onNodeClick}
+    />
+  );
+};
+
+export default DragHandleFlow;