Support markdown content in cards

[Greenheart]

This component might help us solve this: https://github.com/pablo-abc/svelte-markdown

Then we could customize the renderers to output styled elements, and simply returning <slot/> for markdown formatting we don't want to support.

[Greenheart]

Benefits

• Adding clickable links would allow scenarios to create a learning experience, where you can introduce concepts and link to resources for more in-depth info. This might unlock new use cases for the game and the engine.
• Possibility to add emphasis like italic and bold text. Could be abused, but could also be a nice touch if used well.

Drawbacks

• Slightly increased complexity of the project, more moving parts to maintain
• Slightly larger frontend app bundle size (though barely not any noticeable impact on performance)