chore: merge blocksuite source code (#9213)

blocksuite/playground/examples/basic/page/main.ts

@@ -0,0 +1,13 @@
+import '../../../style.css';
+
+import { createEmptyDoc, PageEditor } from '@blocksuite/presets';
+import { Text } from '@blocksuite/store';
+
+const doc = createEmptyDoc().init();
+const editor = new PageEditor();
+editor.doc = doc;
+document.body.append(editor);
+
+const paragraphs = doc.getBlockByFlavour('affine:paragraph');
+const paragraph = paragraphs[0];
+doc.updateBlock(paragraph, { text: new Text('Hello World!') });