[ic-badge] - Review styling of badge in High Contrast mode

## Summary
The current styling of ic-badge in high contrast mode should be reviewed.

## 💬 Description
With the current styling, it is hard to distinguish the badge. For example:

there are a few possible options to explore:

1) could an outline be added around the badge?
2) should the badge detail use the high contrast text colour? For example, MUI does this:

3) Should the colour change depending on the variant? Currently an "error", "warning", etc variant all display the same & have no visual difference in high contrast mode. This is inconsistent with other components such as ic-alert and validation on -ic-text-field:

## 📝 Acceptance Criteria
To be defined when review complete

*Given*
*When*
*Then*

## ✏ Designs
If there's a Figma design file (or other mock-up), include it here.

## Additional Info
Can be investigated by development, but may want to run the solutions past design

Start by reviewing the ic-badge high-contrast styling described in the issue and compare it with ic-alert and validation on -ic-text-field. Evaluate the outline, high-contrast text colour, and variant-specific colour options, then confirm the preferred approach with design. Done means the review has a decided direction and defined acceptance criteria.

Written by the indexing model from the issue text.