fix(ui): folder view toggle button styles overridden due to equal specificity (#15544)

### What

Folder view toggle buttons render with inconsistent padding across
different environments due to CSS cascade order differences.

### Why

The `.folder-view-toggle-button` selector has equal specificity to
`.btn`, so whichever CSS loads last wins. Different build tools and
environments load CSS in different orders, causing the padding to apply
inconsistently.

### How

Increased selector specificity from `.folder-view-toggle-button` to
`.btn.folder-view-toggle-button`.

Fixes #15523

Author: PatrikKozak

packages/ui/src/elements/FolderView/ToggleViewButtons/index.scss

@@ -1,7 +1,7 @@
 @import '../../../scss/styles.scss';
 
 @layer payload-default {
-  .folder-view-toggle-button {
+  .btn.folder-view-toggle-button {
     padding: 0;
     background-color: transparent;