Adds Contaminant Detector HUD (#15970)

code/game/objects/effects/decals/Cleanable/humans.dm

@@ -193,6 +193,7 @@ var/global/list/image/splatter_cache=list()
 
 	icon = blood
 	cut_overlays()
+	add_overlay(janhud)
 	add_overlay(giblets)
 
 /obj/effect/decal/cleanable/blood/gibs/up

code/game/objects/effects/decals/Cleanable/tracks.dm

@@ -130,6 +130,7 @@ var/global/list/image/fluidtrack_cache=list()
 
 /obj/effect/decal/cleanable/blood/tracks/update_icon()
 	cut_overlays()
+	add_overlay(janhud)
 	color = "#FFFFFF"
 	var/truedir=0
 

code/game/objects/effects/decals/cleanable.dm

@@ -12,6 +12,7 @@ generic_filth = TRUE means when the decal is saved, it will be switched out for
 	var/generic_filth = FALSE
 	var/age = 0
 	var/list/random_icon_states = list()
+	var/list/janhud = list()
 
 /obj/effect/decal/cleanable/Initialize(var/mapload, var/_age)
 	if(!isnull(_age))
@@ -20,10 +21,13 @@ generic_filth = TRUE means when the decal is saved, it will be switched out for
 		src.icon_state = pick(src.random_icon_states)
 	if(!mapload || !config.persistence_ignore_mapload)
 		SSpersistence.track_value(src, /datum/persistent/filth)
+	janhud += gen_hud_image(ingame_hud, src, "janhud[rand(1,9)]", plane = PLANE_JANHUD)
+	add_overlay(janhud)
 	. = ..()
 
 /obj/effect/decal/cleanable/Destroy()
 	SSpersistence.forget_value(src, /datum/persistent/filth)
+	cut_overlays()
 	. = ..()
 
 /obj/effect/decal/cleanable/clean_blood(var/ignore = 0)