Fixes overlay glitch in clipboards and allows mice to be butchered (#41322)

As the title suggests, papers no longer disappear once added to a clipboard, and dead mice, the reagent produced as a result of killing them, can now be butchered. The code for the latter did exist, but the functionality did not, as only living mobs can use the butchering proc.

cl Youbar
fix: clipboards now display held papers properly
fix: mice can be butchered
/cl

code/modules/food_and_drinks/food/snacks/meat.dm

@@ -150,6 +150,11 @@
 	name = "monkey meat"
 	foodtype = RAW | MEAT
 
+/obj/item/reagent_containers/food/snacks/meat/slab/mouse
+	name = "mouse meat"
+	desc = "A slab of mouse meat. Best not eat it raw."
+	foodtype = RAW | MEAT | GROSS
+
 /obj/item/reagent_containers/food/snacks/meat/slab/corgi
 	name = "corgi meat"
 	desc = "Tastes like... well you know..."

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

@@ -13,7 +13,7 @@
 	see_in_dark = 6
 	maxHealth = 5
 	health = 5
-	butcher_results = list(/obj/item/reagent_containers/food/snacks/meat/slab = 1)
+	butcher_results = list(/obj/item/reagent_containers/food/snacks/meat/slab/mouse = 1)
 	response_help  = "pets"
 	response_disarm = "gently pushes aside"
 	response_harm   = "splats"
@@ -113,5 +113,16 @@
 	foodtype = GROSS | MEAT | RAW
 	grind_results = list("blood" = 20, "liquidgibs" = 5)
 
+/obj/item/reagent_containers/food/snacks/deadmouse/attackby(obj/item/I, mob/user, params)
+	if(I.is_sharp() && user.a_intent == INTENT_HARM)
+		if(isturf(loc))
+			new /obj/item/reagent_containers/food/snacks/meat/slab/mouse(loc)
+			to_chat(user, "<span class='notice'>You butcher [src].</span>")
+			qdel(src)
+		else
+			to_chat(user, "<span class='warning'>You need to put [src] on a surface to butcher it!</span>")
+	else
+		return ..()
+
 /obj/item/reagent_containers/food/snacks/deadmouse/on_grind()
 	reagents.clear_reagents()

code/modules/paperwork/clipboard.dm

@@ -27,12 +27,14 @@
 
 /obj/item/clipboard/update_icon()
 	cut_overlays()
+	var/list/dat = list()
 	if(toppaper)
-		add_overlay(toppaper.icon_state)
-		copy_overlays(toppaper)
+		dat += toppaper.icon_state
+		dat += toppaper.overlays.Copy()
 	if(haspen)
-		add_overlay("clipboard_pen")
-	add_overlay("clipboard_over")
+		dat += "clipboard_pen"
+	dat += "clipboard_over"
+	add_overlay(dat)
 
 
 /obj/item/clipboard/attackby(obj/item/W, mob/user, params)