## Summary
- Adds `public virtual bool Murderer => Kills >= 5` property to `Mobile`, replacing ~30 scattered `Kills >= 5` / `Kills < 5` magic-number checks across the codebase
- `BaseCreature` overrides `Murderer` to also return `true` when `AlwaysMurderer` is set
- Updates `Corpse` serialization to v15, storing `_murderer` as a `bool` field (migrated from `int Kills >= 5` in earlier versions)
### Summary
Converts ethics system to entity persistence and removes the persistence item.
### TODO
1. The enable/disable toggle doesn't propagate to all code that does Ethics checks (notoriety, pvp, etc).
2. We need commands to remove them from an ethic.
