Bookmark name changing moves it to bottom

### Which version of floccus are you using?

5.10.3

### How many bookmarks do you have, roughly?

2700

### Are you using other means to sync bookmarks in parallel to floccus?

No

### Sync method

Google Drive

### Which browser are you using? In case you are using the phone App, specify the Android or iOS version and device please.

Windows: Cent Browser, Catsxp Browser 153.0.8010.40, Vivaldi 152.0.7977.112, Chrome 153.0.8010.37

### Which version of Nextcloud Bookmarks are you using? (if relevant)

_No response_

### Which version of Nextcloud? (if relevant)

_No response_

### What kind of WebDAV server are you using? (if relevant)

_No response_

### Describe the Bug

Changing name of existing bookmark. After sync on another browsers, that bookmark changes name, but always moves to the very bottom. That bottom position of bookmark saves and syncs across browsers if clean sync (without bookmarks in browser). If change bookmark's URL, after sync, bookmark stays in the same place. Only name changing causes that behavior.

### Expected Behavior

Changing name of existing bookmark. Name changes. Bookmark leaves in place.

### To Reproduce

[floccus-5.10.3-2026-09-14-full.log](https://github.com/user-attachments/files/32184352/floccus-5.10.3-2026-09-14-full.log)

https://github.com/user-attachments/assets/14578d06-2afc-4973-9500-450b44ecc448

### Debug log provided

- [x] I have provided a debug log file

Start by reproducing the rename-and-sync scenario described for floccus 5.10.3 across the listed browsers, then inspect the attached debug log for the sync steps that move the bookmark. Done means changing only a bookmark's name updates its name while preserving its existing position after synchronization.

Written by the indexing model from the issue text.