[feat]: Add default active styles for Button component

[Gianthard-cyh]

Feature description

Description

Currently, the Button component in shadcn/ui does not provide any default :active styles.
When users click or tap a button, there is no visual feedback for the active state, which slightly affects the overall interaction experience, especially on mobile devices.

Motivation

Adding a subtle default active style (e.g. slight scale-down, brightness change, or ring effect) would:

• Improve perceived responsiveness
• Provide better interaction feedback
• Align with common UX practices for interactive components

Suggested Implementation (Optional)

Add active:scale-[0.98] active:brightness-95 as a default class for button components.
(or a slight inset shadow / darker shade / tiny scale-down), applied optionally based on variant or theme to respect design flexibility.

I can open a PR if this is something maintainers would like to include.

Affected component/components

Button

Additional Context

There is also a good discussion about whether active/pressed states are still necessary in modern UI design here:
https://ux.stackexchange.com/questions/148437/do-we-still-need-an-active-pressed-state-for-a-button

Before submitting

• I've made research efforts and searched the documentation
• I've searched for existing issues and PRs

[shivam-070208]

Assign this to me