Petra should be okay after rP21048 & rP21049.
The `TargetIsAlive` function needs a little more thought. E.g., makes sense for heal and repair---
Verify that:
- Petra works as usual by playing some test games (or observing).
- A relic shows as panel entity with the capture bar.
- A wonder shows as panel entitity with capture and health bars.
- A hero shows as panel entity with the health bar.
- Relics cannot be attacked anymore, but probably not for return resource or guardingcan be captured.