Fix organs having no DNA and become bloody when violently removed (#78519)

## About The Pull Request
Fixes #75585

Organs now spawn with DNA that can be scanned by a forensic scanner.
Robotic organs have no DNA and organic organs with no prior owner spawn
with synthetic DNA. If the syntenic DNA organ is inserted into someone,
the organ inherits the owners DNA. This override can only happen once
and only if the organ has never been used.

Any organ removed is covered in blood, unless it's surgically removed. I
had to give the `NO_BLOOD_ON_ITEM` to hearts since the icon was
glitching out with blood decals on it. It also appears that moth wings
(and maybe normal ones?) do not inherit blood decals naturally despite
being covered in blood. No idea why, but that's out of scope for this
PR.

## Why It's Good For The Game
Forensics scanning is now more robust. 

## Changelog
🆑
fix: Fix organs having no DNA and become bloody when violently removed. 
/🆑

---------

Co-authored-by: Jacquerel <hnevard@gmail.com>

code/__DEFINES/surgery.dm

@@ -24,6 +24,8 @@
 #define ORGAN_UNREMOVABLE (1<<8)
 /// Can't be seen by scanners, doesn't anger body purists
 #define ORGAN_HIDDEN (1<<9)
+/// Has the organ already been inserted inside someone
+#define ORGAN_VIRGIN (1<<10)
 
 /// Helper to figure out if a limb is organic
 #define IS_ORGANIC_LIMB(limb) (limb.bodytype & BODYTYPE_ORGANIC)

code/modules/forensics/_forensics.dm

@@ -232,6 +232,8 @@
 /datum/forensics/proc/check_blood()
 	if(!parent || !isitem(parent.resolve()))
 		return
+	if(isorgan(parent.resolve())) // organs don't spawn with blood decals by default
+		return
 	if(!length(blood_DNA))
 		return
 	var/atom/parent_atom = parent.resolve()

code/modules/surgery/organs/_organ.dm

@@ -6,6 +6,8 @@
 	throwforce = 0
 	/// The mob that owns this organ.
 	var/mob/living/carbon/owner = null
+	/// The cached info about the blood this organ belongs to
+	var/list/blood_dna_info = list("Synthetic DNA" = "O+") // not every organ spawns inside a person
 	/// The body zone this organ is supposed to inhabit.
 	var/zone = BODY_ZONE_CHEST
 	/**
@@ -14,7 +16,7 @@
 	 */
 	var/slot
 	/// Random flags that describe this organ
-	var/organ_flags = ORGAN_ORGANIC | ORGAN_EDIBLE
+	var/organ_flags = ORGAN_ORGANIC | ORGAN_EDIBLE | ORGAN_VIRGIN
 	/// Maximum damage the organ can take, ever.
 	var/maxHealth = STANDARD_ORGAN_THRESHOLD
 	/**
@@ -75,6 +77,9 @@ INITIALIZE_IMMEDIATE(/obj/item/organ)
 			volume = reagent_vol,\
 			after_eat = CALLBACK(src, PROC_REF(OnEatFrom)))
 
+	if(!IS_ROBOTIC_ORGAN(src))
+		add_blood_DNA(blood_dna_info)
+
 /*
  * Insert the organ into the select mob.
  *
@@ -100,6 +105,14 @@ INITIALIZE_IMMEDIATE(/obj/item/organ)
 	receiver.organs_slot[slot] = src
 	owner = receiver
 
+	if(!IS_ROBOTIC_ORGAN(src) && (organ_flags & ORGAN_VIRGIN))
+		blood_dna_info = receiver.get_blood_dna_list()
+		// need to remove the synethic blood DNA that is initialized
+		// wash also adds the blood dna again
+		wash(CLEAN_TYPE_BLOOD)
+		organ_flags &= ~ORGAN_VIRGIN
+
+
 	// Apply unique side-effects. Return value does not matter.
 	on_insert(receiver, special)
 
@@ -168,6 +181,9 @@ INITIALIZE_IMMEDIATE(/obj/item/organ)
 	SEND_SIGNAL(src, COMSIG_ORGAN_REMOVED, organ_owner)
 	SEND_SIGNAL(organ_owner, COMSIG_CARBON_LOSE_ORGAN, src, special)
 
+	if(!IS_ROBOTIC_ORGAN(src) && !(item_flags & NO_BLOOD_ON_ITEM) && !QDELING(src))
+		AddElement(/datum/element/decal/blood)
+
 	var/list/diseases = organ_owner.get_static_viruses()
 	if(!LAZYLEN(diseases))
 		return
@@ -228,6 +244,14 @@ INITIALIZE_IMMEDIATE(/obj/item/organ)
 /obj/item/organ/proc/on_surgical_removal(mob/living/user, mob/living/carbon/old_owner, target_zone, obj/item/tool)
 	SHOULD_CALL_PARENT(TRUE)
 	SEND_SIGNAL(src, COMSIG_ORGAN_SURGICALLY_REMOVED, user, old_owner, target_zone, tool)
+	RemoveElement(/datum/element/decal/blood)
+
+/obj/item/organ/wash(clean_types)
+	. = ..()
+
+	// always add the original dna to the organ after it's washed
+	if(!IS_ROBOTIC_ORGAN(src) && (clean_types & CLEAN_TYPE_BLOOD))
+		add_blood_DNA(blood_dna_info)
 
 /obj/item/organ/process(seconds_per_tick, times_fired)
 	return

code/modules/surgery/organs/internal/heart/_heart.dm

@@ -6,7 +6,7 @@
 	visual = FALSE
 	zone = BODY_ZONE_CHEST
 	slot = ORGAN_SLOT_HEART
-
+	item_flags = NO_BLOOD_ON_ITEM
 	healing_factor = STANDARD_ORGAN_HEALING
 	decay_factor = 2.5 * STANDARD_ORGAN_DECAY //designed to fail around 6 minutes after death