Hidden link remains when deleting link in markdown widget

**Describe the bug**

When a link is created in the markdown widget in rich text mode and later deleted, the link is not fully removed. The text disappears, but the hyperlink itself remains. This becomes visible when switching to markdown mode.

**To Reproduce**

1. Open page with markdown widget
2. Insert a link inside
3. Delete the linked text - in rich text mode
4. Switch to markdown mode to see that hyperlink is not deleted

**Expected behavior**

Both the text and the hyperlink should be removed when deleting a link.

**Screenshots**

https://github.com/user-attachments/assets/81ad30a6-6ee0-4cca-a412-3491faa33394

**Applicable Versions:**

- Decap CMS version: 3.8.3
- Git provider: GitHub
- OS: macOS 26.0.1
- Browser version: Chrome 141

**CMS configuration**

{name: caption, widget: markdown, i18n: true, required: false, buttons: ["link"], editor_components: []},

Start at the markdown widget's rich-text editor entry point and reproduce the issue using the configuration in the report. Check the generated markdown after deleting linked text in rich text mode, then verify that both the text and hyperlink are absent when switching to markdown mode.

Written by the indexing model from the issue text.