fix(expand-collapse-release-groups): prevent button text selection (#1051)

_Note: Code and description were written with AI-tools_

### Description
Prevent accidental highlighting and text selection on the
expand/collapse toggle button when clicking release groups and releases.

### Key Changes
- Add `user-select: none` to the toggle button element in
`create_button`.

### Verification
- Validated with `oxlint` (0 errors, 0 warnings).
- Verified that rapid clicks or drag gestures on the toggle button do
not highlight the glyph.

### Version Bump
- Bumped `expand-collapse-release-groups.user.js` version from
`2026.7.7.1` to `2026.8.28.1`.

Author: chaban-mb

expand-collapse-release-groups.user.js

@@ -3,7 +3,7 @@
 // @description  See what's inside a release group without having to follow its URL. Also adds convenient edit links for it.
 // @namespace    http://userscripts.org/users/266906
 // @author       Michael Wiencek <mwtuea@gmail.com>
-// @version      2026.7.7.1
+// @version      2026.8.28.1
 // @license      GPL
 // @downloadURL  https://raw.githubusercontent.com/murdos/musicbrainz-userscripts/master/expand-collapse-release-groups.user.js
 // @updateURL    https://raw.githubusercontent.com/murdos/musicbrainz-userscripts/master/expand-collapse-release-groups.user.js
@@ -87,6 +87,7 @@ function create_button(url, dom_callback, success_callback, error_callback) {
     button.style.cursor = 'pointer';
     button.style.marginRight = '4px';
     button.style.color = '#777';
+    button.style.userSelect = 'none';
 
     button.addEventListener(
         'mousedown',