SelectButton last buttons lacks inline end border in RTL mode in presets other than Aura

Describe the bug

In RTL mode and presets other than Aura, the last button lacks the inline end border.

A CSS seems to be missing.

Pull Request Link

No response

Reason for not contributing a PR

• Lack of time
• Unsure how to implement the fix/feature
• Difficulty understanding the codebase
• Other

Other Reason

I think it should be fixed in @primeuix/themes?

The fix seems to simply have:

.p-selectbutton .p-togglebutton:last-child {
  border-inline-end-width: 1px;
}

Reproducer

https://stackblitz.com/edit/github-n3zu3rpq-tmeerazz?file=src%2Fapp%2Fapp.component.html,src%2Fstyles.scss

Environment

macOS 15.7

Angular version

20.3.1

PrimeNG version

v20

Node version

22.15.0

Browser(s)

No response

Steps to reproduce the behavior

1. Go to the SelectButton demo in RTL mode and a preset other than Aura, for instance Lara, or to the reproducer link
2. Observe that the last buttons does not have an inline end border

Expected behavior

The last button should have the inline end border in RTL mode in themes other than Aura.

Start with the SelectButton demo and the linked StackBlitz reproducer, especially src/app/app.component.html and src/styles.scss, then trace the component styling into @primeuix/themes. Verify the RTL rendering with the Lara preset and other non-Aura presets; done means the last button has the inline end border in each case.