Added downed enemies after leg destruction

I added a downed state for enemies that lose a leg. Instead of treating the injury as an ordinary stance change, the body falls toward the damaged side and stays down.

A downed enemy can still be dangerous. Crawling costs four times the usual time units, and its aim receives a 25 percent penalty. Losing both arms as well prevents it from crawling.

“Destroying a leg now leaves an enemy downed, with slower crawling and less accurate fire.”

This is separate from going prone deliberately. Prone is a tactical choice; being downed is the consequence of damage, and the enemy cannot simply stand back up.

I carried the state through the animation, targeting rules, HUD and combat log so the visible fall and the combat consequences agree. The clip is a staged demonstration of the native damage response, rather than a player-fired attack.