refactor: image preview plugin (#3457)

plugins/image-preview/src/index.ts

@@ -0,0 +1,18 @@
+import type { PluginContext } from '@toeverything/plugin-infra/entry';
+import { createElement } from 'react';
+import { createRoot } from 'react-dom/client';
+
+import { App } from './app';
+
+export const entry = (context: PluginContext) => {
+  context.register('editor', (div, editor) => {
+    const root = createRoot(div);
+    root.render(createElement(App, { page: editor.page }));
+    return () => {
+      root.unmount();
+    };
+  });
+  return () => {
+    // do nothing
+  };
+};