CobbleStacker

Fix: Server crash caused by Watchdog timeout

The server was crashing with a Watchdog error because CobbleStacker was modifying the list of entities (removing/discarding items) while still looping through it. This is like pulling cards out of a deck while someone else is counting them — it causes the game to freeze and eventually the Watchdog kills the server
for being unresponsive.

What we changed: The auto-clear and force-clear systems now first make a list of all the items that need to be removed, and only then actually remove them after the loop is done. This prevents the freeze entirely.