Fix fire exploit being extinguished by pAIs, borgs, and simple animals (#60852)

* Fix fire being extinguished by pAIs, borgs, and simple animals

* Add trait TRAIT_NOFIRE_SPREAD

* Add NOFIRE_SPREAD traits to simple and silicon mob types

* Refactor spreadFire proc to use check TRAIT_NOFIRE_SPREAD

code/__DEFINES/traits.dm

@@ -199,6 +199,7 @@ Remember to update _globalvars/traits.dm if you're adding/removing/renaming trai
 #define TRAIT_PIERCEIMMUNE "pierce_immunity"
 #define TRAIT_NODISMEMBER "dismember_immunity"
 #define TRAIT_NOFIRE "nonflammable"
+#define TRAIT_NOFIRE_SPREAD "no_fire_spreading"
 #define TRAIT_NOGUNS "no_guns"
 #define TRAIT_NOHUNGER "no_hunger"
 #define TRAIT_NOMETABOLISM "no_metabolism"

code/modules/mob/living/living.dm

@@ -1442,6 +1442,10 @@
 	if(!istype(L))
 		return
 
+	// can't spread fire to mobs that don't catch on fire
+	if(HAS_TRAIT(L, TRAIT_NOFIRE_SPREAD) || HAS_TRAIT(src, TRAIT_NOFIRE_SPREAD))
+		return 
+
 	if(on_fire)
 		if(L.on_fire) // If they were also on fire
 			var/firesplit = (fire_stacks + L.fire_stacks)/2

code/modules/mob/living/silicon/silicon.dm

@@ -59,6 +59,7 @@
 	add_sensors()
 	ADD_TRAIT(src, TRAIT_ADVANCEDTOOLUSER, ROUNDSTART_TRAIT)
 	ADD_TRAIT(src, TRAIT_MARTIAL_ARTS_IMMUNE, ROUNDSTART_TRAIT)
+	ADD_TRAIT(src, TRAIT_NOFIRE_SPREAD, SPECIES_TRAIT)
 
 /mob/living/silicon/Destroy()
 	QDEL_NULL(radio)

code/modules/mob/living/simple_animal/simple_animal.dm

@@ -178,6 +178,7 @@
 		AddComponent(/datum/component/personal_crafting)
 		ADD_TRAIT(src, TRAIT_ADVANCEDTOOLUSER, ROUNDSTART_TRAIT)
 		ADD_TRAIT(src, TRAIT_CAN_STRIP, ROUNDSTART_TRAIT)
+	ADD_TRAIT(src, TRAIT_NOFIRE_SPREAD, SPECIES_TRAIT)
 
 	if(speak)
 		speak = string_list(speak)