Feature: Add additional ui_level to show preset/custom PNGs for Low/Medium/High detections.

### Prerequisites

- [x] I have read [CONTRIBUTING.md](https://github.com/EFForg/rayhunter/blob/main/CONTRIBUTING.md)

### What problem does this feature solve or what does it enhance?

This feature improves alerting by making the UI image reflect detection severity, not just the thin status bar.

Adds customization and personalization.

Is just more fun in general.

### Proposed Solution

Add a new UI level that renders a PNG icon and switches between different PNGs based on DisplayState.

If there's enough people that are interested in this I can make a pull request.

Proof of concept -


### Alternatives Considered

_No response_