Fix synthflesh patch unhusking, improved feedback (#90514)

## About The Pull Request

- Fixes application of synthflesh patches for unhusking mobs, adjusts
purity to allow one medigel to dehusk one corpse.
- Improved information on containers about the requirements to unhusk,
and added feedback for the player to help guide the proper usage of the
synthflesh.
- It will give a warning if they are using it in a method that would
waste the synthflesh and fail to unhusk.

## Why It's Good For The Game

- Fixes patches.
- Provide better feedback on why failure to dehusk occurs. Currently the
player is provided no information about why it failed (such as purity,
quantity, burn damage) nor how to resolve it.

## Changelog

🆑 LT3
fix: Synthflesh patches unhusk corpses as expected
qol: Better information and feedback about de-husking corpses
/🆑

---------

Co-authored-by: MrMelbert <51863163+MrMelbert@users.noreply.github.com>

code/modules/reagents/reagent_containers/patch.dm

@@ -170,6 +170,10 @@
 
 	parent.reagents.trans_to(owner, transfer_per_second, methods = PATCH, show_message = show_message)
 
+// delivers all of the patch's contents at once
+/datum/embedding/med_patch/instant
+	transfer_per_second = /obj/item/reagent_containers/applicator/patch::volume
+
 /obj/item/reagent_containers/applicator/patch/libital
 	name = "libital patch (brute)"
 	desc = "A pain reliever. Does minor liver damage. Diluted with Granibitaluri."
@@ -184,9 +188,24 @@
 
 /obj/item/reagent_containers/applicator/patch/synthflesh
 	name = "synthflesh patch"
-	desc = "Helps with brute and burn injuries. Slightly toxic."
+	desc = "Helps with brute and burn injuries. Slightly toxic. Three patches applied can restore a corpse husked by burns."
 	list_reagents = list(/datum/reagent/medicine/c2/synthflesh = 20)
+	list_reagents_purity = 1
 	icon_state = "bandaid_both"
+	embed_type = /datum/embedding/med_patch/instant //synthflesh effects occur on the initial apply only, so we need to apply it all at once
+
+/obj/item/reagent_containers/applicator/patch/canconsume(mob/eater, mob/user)
+	. = ..()
+	if(!iscarbon(eater))
+		return
+	var/datum/reagent/medicine/c2/synthflesh/synthflesh_patch = reagents.has_reagent(/datum/reagent/medicine/c2/synthflesh)
+	if(!synthflesh_patch)
+		return
+	// Check mob damage for synthflesh unhusking
+	var/mob/living/carbon/carbies = eater
+	if(HAS_TRAIT_FROM(carbies, TRAIT_HUSK, BURN) && carbies.getFireLoss() > UNHUSK_DAMAGE_THRESHOLD * 2.5)
+		// give them a warning if the mob is a husk but synthflesh won't unhusk yet
+		carbies.visible_message(span_boldwarning("[carbies]'s burns need to be repaired first before synthflesh will unhusk it!"))
 
 /obj/item/reagent_containers/applicator/patch/ondansetron
 	name = "ondansetron patch"