fix link hover style issue in tile grid

[ntno]

when a linked tile is hovered we should highlight it just like links are highlighted when links are hovered on.
we should NOT highlight the figcaption as it could contain a different link from the tile link

Description

linked image tile on hover

linked image tile on hover when image is broken

linked image tile when image is valid but slow to load

Testing

added examples on palette pages to test contrast in alternate palettes updated existing unit tests

• [ ] This change adds test coverage for new/changed/fixed functionality

Checklist

• [x] I have added documentation for new/changed functionality in this PR or in mkdocs-terminal/documentation
• [ ] All active GitHub checks for tests, formatting, and security are passing
• [x] ran tox locally