Fixed a bug that caused entities to survive server restarts.

Fixed a double-spawn race condition bug at startup.

Fixed an issue where, when a player disconnected, the entity remained in the world without being cleared. Upon reconnecting, a new entity would spawn without removing the previous one.

Added an orphaned entity cleanup at startup that, upon server startup, searches all worlds for SmartPets-marked entities that are not tracked on the active map and removes them.