Adds the craftable MOD soul shard core. (#91023)

## About The Pull Request

If you examine a soul shard closely, you can learn to craft the MOD soul
shard core. It takes the same basic ingredients as other MOD cores, but
uses a soul shard. It is powered by your own soul, which drains your
sanity to provide charge (if mood is disabled in the config, it's
practically equivalent to an infinite core).

Crafting one ejects any shades in the shard (because that's the simplest
behavior that doesn't require a substantial refactor to crafting or
modsuit code).

Depending on the kind of shard used, certain roles get negatively
impacted by using a modsuit with such a core.
- Cult soul shards wrack non-magical roles (anyone that isn't a cultist,
heretic, heretic minion, or wizard) with horrible agony (a -20 moodlet
that expires 10 seconds after turning the suit off)
- Holy soul shards wrack cultists and heretics with horrible agony,
while wizards are put at unease (-3 mood)
- Wizard soul shards have no negative impact on anyone
- If someone were to VV a soul shard to have the heretic theme (only
used by rusted harvesters), it would be functionally identical to the
cult shard

Soulless mobs (liches, people who lost with the cursed russian revolver,
and people who died from casting Soul Tap too many times) have no soul
for the core to draw power from.

Also gives the wizard modsuit a soul core.

## Why It's Good For The Game

Provides a neat but caveat-rich way to utilize soul shards, especially
for players who have no way to obtain construct shells absent a cult or
wizard to create them.

code/modules/mod/mod_core.dm

@@ -509,3 +509,168 @@
 	var/flower_boots = new chosen_type(get_turf(mod.wearer))
 	animate(flower_boots, alpha = 0, 1 SECONDS)
 	QDEL_IN(flower_boots, 1 SECONDS)
+
+/obj/item/mod/core/soul
+	name = "MOD soul shard core"
+	desc = "A soul shard haphazardly jammed into a hand-crafted MOD core frame."
+	icon_state = "mod-core-soul"
+	icon_state_preview = "mod-core-soul-preview"
+	var/base_desc
+	var/theme = THEME_CULT
+	greyscale_config = /datum/greyscale_config/mod_core_soul
+	greyscale_colors = "#ff0000"
+
+/obj/item/mod/core/soul/Initialize(mapload)
+	. = ..()
+	base_desc = desc
+	update_appearance(UPDATE_DESC)
+
+/obj/item/mod/core/soul/update_desc(updates)
+	. = ..()
+	desc = base_desc
+	switch(theme)
+		if(THEME_CULT)
+			desc += " You can feel unholy energies trying to tear something away from you."
+		if(THEME_HOLY)
+			desc += " It emanates a divine aura that defies souls tainted by darker forces."
+		if(THEME_WIZARD)
+			desc += " Yet another foray by the Wizard Federation into the dangerous field of soul magic."
+		if(THEME_HERETIC)
+			desc += " The surface of the shard shines with glimpses of things which never were, yet have always been."
+		else
+			desc += " Or at least, that's what it should be. <i>Somebody</i> must have set a variable incorrectly."
+
+/obj/item/mod/core/soul/update_greyscale()
+	switch(theme)
+		if(THEME_CULT)
+			greyscale_colors = "#ff0000"
+		if(THEME_HOLY)
+			greyscale_colors = "#0000ff"
+		if(THEME_WIZARD)
+			greyscale_colors = "#ff00ff"
+		if(THEME_HERETIC)
+			greyscale_colors = "#00ff00"
+	return ..()
+
+/obj/item/mod/core/soul/CheckParts(list/parts_list, datum/crafting_recipe/current_recipe)
+	var/obj/item/soulstone/stone = locate() in parts_list
+	set_theme(stone.theme)
+	for(var/mob/living/basic/shade/shade in stone)
+		shade.forceMove(get_turf(src))
+		shade.visible_message(span_warning("[shade] is ejected from [stone] as it is inserted into [src]!"), span_warning("You are ejected from [stone] as it is inserted into [src]!"))
+	parts_list -= stone
+	qdel(stone)
+	return ..()
+
+/obj/item/mod/core/soul/proc/set_theme(new_theme)
+	theme = new_theme
+	update_appearance(UPDATE_DESC)
+	update_greyscale()
+
+/obj/item/mod/core/soul/charge_source()
+	return CONFIG_GET(flag/disable_human_mood) ? src : mod.wearer?.mob_mood
+
+/obj/item/mod/core/soul/max_charge_amount()
+	return CONFIG_GET(flag/disable_human_mood) ? INFINITY : SANITY_MAXIMUM
+
+/obj/item/mod/core/soul/charge_amount()
+	var/mob/living/wearer = mod.wearer
+	if(!wearer)
+		return 0
+	if(HAS_TRAIT(wearer, TRAIT_NO_SOUL))
+		return 0 // Can't draw from something that isn't there.
+	if(CONFIG_GET(flag/disable_human_mood))
+		return INFINITY
+	var/datum/mood/source = charge_source()
+	return source?.sanity
+
+/obj/item/mod/core/soul/check_charge(amount)
+	if(CONFIG_GET(flag/disable_human_mood))
+		return !!mod.wearer
+	return charge_amount() >= amount * 10 / STANDARD_CELL_CHARGE
+
+/obj/item/mod/core/soul/subtract_charge(amount)
+	var/mob/living/wearer = mod.wearer
+	if(CONFIG_GET(flag/disable_human_mood))
+		return !!wearer
+	var/datum/mood/source = charge_source()
+	source.adjust_sanity(-amount * 10 / STANDARD_CELL_CHARGE)
+	var/backlash_type = get_backlash_type(wearer)
+	if(backlash_type)
+		wearer.add_mood_event("soul_core", backlash_type)
+	else
+		wearer.add_mood_event("soul_core", /datum/mood_event/soul_core_warning)
+	return TRUE
+
+/obj/item/mod/core/soul/get_chargebar_string()
+	var/mob/living/wearer = mod.wearer
+	if(wearer || HAS_TRAIT(wearer, TRAIT_NO_SOUL))
+		return "No power source detected."
+	if(CONFIG_GET(flag/disable_human_mood))
+		return "Infinite"
+	return "[round(charge_amount() / max_charge_amount() * 100, 0.1)]%"
+
+/obj/item/mod/core/soul/get_chargebar_color()
+	switch(theme)
+		if(THEME_CULT)
+			return "red"
+		if(THEME_HOLY)
+			return "blue"
+		if(THEME_WIZARD)
+			return "purple"
+		if(THEME_HERETIC)
+			return "green"
+
+/obj/item/mod/core/soul/proc/get_backlash_type(mob/living/checked)
+	switch(theme)
+		if(THEME_CULT)
+			if(!(IS_CULTIST(checked) || IS_HERETIC(checked) || HAS_MIND_TRAIT(checked, TRAIT_MAGICALLY_GIFTED)))
+				return /datum/mood_event/soul_core_torment
+		if(THEME_HERETIC)
+			if(!(IS_CULTIST(checked) || IS_HERETIC(checked) || HAS_MIND_TRAIT(checked, TRAIT_MAGICALLY_GIFTED)))
+				return /datum/mood_event/soul_core_torment/heretic
+		if(THEME_HOLY)
+			if(IS_CULTIST(checked) || IS_HERETIC(checked))
+				return /datum/mood_event/soul_core_torment
+			if(IS_WIZARD(checked))
+				return /datum/mood_event/soul_core_discomfort
+
+/obj/item/mod/core/soul/get_charge_icon_state()
+	switch(round(charge_amount() / max_charge_amount(), 0.01))
+		if(0.75 to INFINITY)
+			return "high"
+		if(0.5 to 0.75)
+			return "mid"
+		if(0.25 to 0.5)
+			return "low"
+		if(0.02 to 0.25)
+			return "very_low"
+
+	return "empty"
+
+/obj/item/mod/core/soul/vv_edit_var(vname, vval)
+	. = ..()
+	if(vname == NAMEOF(src, theme))
+		update_appearance(UPDATE_DESC)
+		update_greyscale()
+
+/datum/mood_event/soul_core_torment
+	description = "IT BURNS!! IT BURNS!! THE DEEPEST DEPTHS OF MY BEING!! IT BURNS!!"
+	mood_change = -20
+	timeout = 10 SECONDS
+
+/datum/mood_event/soul_core_torment/heretic
+	description = "GET OUT OF MY HEAD GET OUT OF MY HEAD GET OUT OF MY HEAD!!"
+
+/datum/mood_event/soul_core_discomfort
+	description = "I'm no fan of these divine powers breathing down my neck."
+	mood_change = -3
+	timeout = 10 SECONDS
+
+/datum/mood_event/soul_core_warning
+	description = "I can feel my modsuit siphoning my energy. I'd better keep my spirits high."
+	mood_change = 0
+	timeout = 10 SECONDS
+
+/obj/item/mod/core/soul/wizard
+	theme = THEME_WIZARD