Spiders can now be tamed and ridden (#95194)

## About The Pull Request
This lets people ride and tame spiders by feeding them mouse, lizard,
moth, fly, and worm meat. You can only do this when a spider is a
spiderling or young; once it's fully grown, it's no longer possible.

This also refactors some tameable code to use `TRAIT_TAMED` instead of
setting variables on mobs individually.

## Why It's Good For The Game
It looks cool.

<img width="1920" height="1080" alt="dreamseeker_97k7fgzdhv"
src="https://github.com/user-attachments/assets/87d53102-468d-4dd7-b0a7-004f9a98df17"
/>


## Changelog
🆑
add: Spiders can now be tamed and ridden. They eat mouse, lizard, moth,
fly, and worm meat and can only be tamed when they are spiderlings or
young.
code: Refactored tameable code to use TRAIT_TAMED instead of setting
individual variables on each mob.
/🆑

code/modules/mob/living/basic/vermin/mouse.dm

@@ -28,8 +28,6 @@
 
 	ai_controller = /datum/ai_controller/basic_controller/mouse
 
-	/// Whether this rat is friendly to players
-	var/tame = FALSE
 	/// What color our mouse is. Brown, gray and white - leave blank for random.
 	var/body_color
 	/// Does this mouse contribute to the ratcap?
@@ -63,7 +61,8 @@
 		SSmobs.cheeserats |= src
 	ADD_TRAIT(src, TRAIT_VENTCRAWLER_ALWAYS, INNATE_TRAIT)
 
-	src.tame = tame
+	if(tame)
+		ADD_TRAIT(src, TRAIT_TAMED, INNATE_TRAIT)
 	if(!isnull(new_body_color))
 		body_color = new_body_color
 	if(isnull(body_color))
@@ -81,7 +80,7 @@
 	AddComponent(/datum/component/swarming, 16, 16) //max_x, max_y
 
 /mob/living/basic/mouse/proc/make_tameable()
-	if (tame)
+	if (HAS_TRAIT(src, TRAIT_TAMED))
 		add_faction(FACTION_NEUTRAL)
 	else
 		var/static/list/food_types = list(/obj/item/food/cheese)
@@ -196,9 +195,9 @@
 
 /// Called when a mouse is hand-fed some cheese, it will stop being afraid of humans
 /mob/living/basic/mouse/tamed(mob/living/tamer, obj/item/food/cheese/cheese)
+	. = ..()
 	new /obj/effect/temp_visual/heart(loc)
 	add_faction(FACTION_NEUTRAL)
-	tame = TRUE
 	try_consume_cheese(cheese)
 	ai_controller.CancelActions() // Interrupt any current fleeing
 
@@ -248,7 +247,7 @@
 
 /// Creates a new mouse based on this mouse's subtype.
 /mob/living/basic/mouse/proc/create_a_new_rat()
-	new /mob/living/basic/mouse(loc, /* tame = */ tame)
+	new /mob/living/basic/mouse(loc, HAS_TRAIT(src, TRAIT_TAMED))
 
 /// Biting into a cable will cause a mouse to get shocked and die if applicable. Or do nothing if they're lucky.
 /mob/living/basic/mouse/proc/try_bite_cable(obj/structure/cable/cable)
@@ -302,7 +301,7 @@
 	contributes_to_ratcap = FALSE
 
 /mob/living/basic/mouse/brown/tom/make_tameable()
-	tame = TRUE
+	ADD_TRAIT(src, TRAIT_TAMED, INNATE_TRAIT)
 	return ..()
 
 /mob/living/basic/mouse/brown/tom/Initialize(mapload)
@@ -312,7 +311,7 @@
 	AddElement(/datum/element/pet_bonus, "squeak")
 
 /mob/living/basic/mouse/brown/tom/create_a_new_rat()
-	new /mob/living/basic/mouse/brown(loc, /* tame = */ tame) // dominant gene
+	new /mob/living/basic/mouse/brown(loc, HAS_TRAIT(src, TRAIT_TAMED)) // dominant gene
 
 /mob/living/basic/mouse/rat
 	name = "rat"