Backspace behaves like Delete in Firefox (cursor does not move backward)

Checklist

• I've looked at the documentation to make sure the behavior isn't documented and expected.
• I'm sure this is an issue with Summernote, not with my app or other dependencies (Angular, Cordova, React, etc.).
• I've searched through the current issues to make sure this hasn't been reported yet.
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Steps to reproduce

1. Initialize the Summernote editor.
2. Create a bulleted list with multiple items, for example:
   1. Example 1
   2. Example 2
   3. Example 3
3. Place the cursor at the end of the second list item (Example 2).
4. Press Backspace

Expected behavior

1. Pressing Backspace should remove content before the cursor.
2. The cursor should move backward and behave consistently with standard editor behavior.
3. The behavior should match how Backspace works in Chrome.

Current behavior

1. Backspace behaves like the Delete key.
2. The cursor stays in the same position instead of moving backward.
3. Content from the next list item (Example 3) is pulled into the current position.

Minimal example reproducing the issue

No response

Environment

• Summernote version: 0.9
• Browser (with version):firefox 146.0.1 (64-bit)
• OS/Platform (with version):Windows 11