fix: split view focus (#11217)

# After:

https://github.com/user-attachments/assets/990d500d-2da7-488e-ac32-dd7bd229f896

# Before:

https://github.com/user-attachments/assets/6676766a-c76a-414b-a35e-53d2cda10c24

tests/blocksuite/e2e/bookmark.spec.ts

@@ -127,6 +127,7 @@ test(
 
     await activeNoteInEdgeless(page, ids.noteId);
     await waitForInlineEditorStateUpdated(page);
+    await focusRichText(page);
     await selectAllByKeyboard(page);
     await copyByKeyboard(page);
     await pressArrowRight(page);