Fix AutoTarget null crash: add FrozenActorLayer to player, FrozenUnderFog on buildings

AttackMoveActivity scanned for frozen actors on a player with no
FrozenActorLayer -> NullReferenceException mid-match. Verified by a full
AI-vs-AI arena match running to completion (BotA won at tick ~10500).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

mods/vinylgod/rules/economy.yaml

@@ -105,6 +105,8 @@ djgrunt:
 
 ^EconBuilding:
 	Inherits: ^EconSprite
+	-HiddenUnderFog:
+	FrozenUnderFog:
 	WithDamageOverlay:
 	FireWarheadsOnDeath:
 		Weapon: BuildingExplode

mods/vinylgod/rules/player.yaml

@@ -4,6 +4,7 @@
 
 player:
 	Inherits: ^baseplayer
+	FrozenActorLayer:
 	DeveloperMode:
 	PlayerResources:
 		DefaultCash: 5000