chore(editor): update default width of page block (#10873)

Close [BS-2498](https://linear.app/affine-design/issue/BS-2498/page-block首次切换时默认宽度为800px)

blocksuite/affine/shared/src/utils/model/doc.ts

@@ -1,3 +1,7 @@
+import {
+  DEFAULT_PAGE_BLOCK_HEIGHT,
+  DEFAULT_PAGE_BLOCK_WIDTH,
+} from '@blocksuite/affine-model';
 import type { Workspace } from '@blocksuite/store';
 import { Text } from '@blocksuite/store';
 
@@ -17,7 +21,13 @@ export function createDefaultDoc(
   });
 
   doc.addBlock('affine:surface', {}, rootId);
-  const noteId = doc.addBlock('affine:note', {}, rootId);
+  const noteId = doc.addBlock(
+    'affine:note',
+    {
+      xywh: `[0, 0, ${DEFAULT_PAGE_BLOCK_WIDTH}, ${DEFAULT_PAGE_BLOCK_HEIGHT}]`,
+    },
+    rootId
+  );
   doc.addBlock('affine:paragraph', {}, noteId);
   // To make sure the content of new doc would not be clear
   // By undo operation for the first time