feature: loading graph structure

src/App.tsx

@@ -7,8 +7,10 @@ import {
   MenuFoldOutlined,
   MenuUnfoldOutlined,
   SaveOutlined,
+  FolderOpenOutlined,
 } from '@ant-design/icons';
 import { saveConceptSketch } from './utils/saveGraph';
+import { loadConceptSketch } from './utils/loadGraph';
 import { useGraphLayersTreeStore } from './stores/TreeStore';
 
 const { Header, Content, Sider } = Layout;
@@ -72,7 +74,19 @@ const App: React.FC = () => {
             </div>
             <Breadcrumb items={graphLevel} />
           </Space>
-          <div style={{ background: '#001529' }}>
+          <div style={{ background: '#001529', display: 'flex' }}>
+            <Button
+              type="text"
+              icon={<FolderOpenOutlined />}
+              onClick={loadConceptSketch}
+              title="Load JSON"
+              style={{
+                fontSize: '16px',
+                width: 32,
+                height: 32,
+                color: colorBgContainer,
+              }}
+            />
             <Button
               type="text"
               icon={<SaveOutlined />}