Danger button

via @shihan007

Allow rendering a button with "danger" styles to give a hint that clicking the button leads to a destruction action.

## Implementation

Use the same styles as message/notification bar.

## Needs discussion

@lo5 We can either allow this via a `danger` attribute to be consistent with other similar attributes like `primary` or we can use `enum` type if further button types will be needed (although I don't see much value in something like success btn etc. personally). Wdyt?

## Workaround for now

Using custom CSS

Start by locating the button implementation and the message/notification bar styles referenced in the issue. Confirm whether a danger attribute or an enum fits the existing button API, then verify that the button renders the matching destructive-action styling and that its behavior remains unchanged.

Written by the indexing model from the issue text.