Datumizes pAI screen images (#89208)

## About The Pull Request
This PR changes pAI screen images (previously called "emotion icon" or
"card overlay") to be datums.

In doing so, I made some changes in how screen images are handled:
* A screen image's name and icon state are separate now, whereas before
the name determined the icon state used.
* Something useful for downstreams: The icon file that a screen image
pulls from default's to tg's icon file for pAI screen images, but can be
overridden if you don't want to put the new screen image in the same
file.
* The FA icon for each screen image is now selected in the datum, rather
than as part of a constant in some far-off TS file.

Additionally, the codebase previously used inconsistent terminology to
refer to these - "card overlay" in one place, "emotion icon" in another,
"image" somewhere else... Now, all of them are called "screen image" or
some variant thereof. "Screen image" is more accurate to what it is
anyways, since it doesn't need to be a face (although 99% of the time,
it will be).

One last thing: The new datum is in its own directory, all by its
lonesome. If you're wondering why I don't just move it out and put it
next to the rest of the pAI module, it's because I plan to datumize some
other pAI stuff (in particular, software and holochassis) in a future
PR. (Though I'll admit, I'm not sure of the current folder location.)

## Why It's Good For The Game
Datumizes some items that really should've been datums in the first
place.

## Changelog

🆑 MichiRecRoom
refactor: Datumized pAI card screen images
/🆑

---------

Co-authored-by: SyncIt21 <110812394+SyncIt21@users.noreply.github.com>

code/modules/pai/card.dm

@@ -14,8 +14,8 @@
 
 	/// Spam alert prevention
 	var/alert_cooldown
-	/// The emotion icon displayed.
-	var/emotion_icon = "off"
+	/// The icon displayed on the card's screen.
+	var/datum/pai_screen_image/screen_image = /datum/pai_screen_image/off
 	/// Any pAI personalities inserted
 	var/mob/living/silicon/pai/pai
 	/// Prevents a crew member from hitting "request pAI" repeatedly
@@ -67,7 +67,7 @@
 	if(QDELETED(src))
 		return
 	pai = null
-	emotion_icon = initial(emotion_icon)
+	screen_image = initial(screen_image)
 	update_appearance()
 
 /obj/item/pai_card/on_saboteur(datum/source, disrupt_duration)
@@ -81,13 +81,13 @@
 
 /obj/item/pai_card/update_overlays()
 	. = ..()
-	. += "pai-[emotion_icon]"
+	. += image(icon = screen_image.icon, icon_state = screen_image.icon_state)
 	if(pai?.hacking_cable)
 		. += "[initial(icon_state)]-connector"
 
 /obj/item/pai_card/vv_edit_var(vname, vval)
 	. = ..()
-	if(vname == NAMEOF(src, emotion_icon))
+	if(vname == NAMEOF(src, screen_image))
 		update_appearance()
 
 /obj/item/pai_card/ui_interact(mob/user, datum/tgui/ui)
@@ -283,7 +283,7 @@
 		return FALSE
 	pai = downloaded
 	RegisterSignal(pai, COMSIG_QDELETING, PROC_REF(on_pai_del))
-	emotion_icon = "null"
+	screen_image = /datum/pai_screen_image/neutral
 	update_appearance()
 	playsound(src, 'sound/effects/pai_boot.ogg', 50, TRUE, -1)
 	audible_message("[src] plays a cheerful startup noise!")

code/modules/pai/datums/screen_icon.dm

@@ -0,0 +1,67 @@
+// Datums describing an icon that is overlaid on a pAI card, to make its screen show something. The
+// player can select between any of these at any time. These are usually faces, but can
+// realistically be anything (similar to an AI's display).
+
+/datum/pai_screen_image
+	// The name to show in the radial menu.
+	var/name
+	// The icon and icon state that is applied to the pAI device when this screen image is selected.
+	var/icon/icon = 'icons/obj/aicards.dmi'
+	var/icon_state
+	// The FontAwesome icon to use next to the "Display" button in the pAI's tgui interface window.
+	var/interface_icon
+
+/datum/pai_screen_image/angry
+	name = "Angry"
+	icon_state = "pai-angry"
+	interface_icon = "angry"
+
+/datum/pai_screen_image/cat
+	name = "Cat"
+	icon_state = "pai-cat"
+	interface_icon = "cat"
+
+/datum/pai_screen_image/extremely_happy
+	name = "Extremely Happy"
+	icon_state = "pai-extremely-happy"
+	interface_icon = "grin-beam"
+
+/datum/pai_screen_image/face
+	name = "Face"
+	icon_state = "pai-face"
+	interface_icon = "grin-alt"
+
+/datum/pai_screen_image/happy
+	name = "Happy"
+	icon_state = "pai-happy"
+	interface_icon = "smile"
+
+/datum/pai_screen_image/laugh
+	name = "Laugh"
+	icon_state = "pai-laugh"
+	interface_icon = "grin-tears"
+
+/datum/pai_screen_image/neutral
+	name = "Neutral"
+	icon_state = "pai-null"
+	interface_icon = "meh"
+
+/datum/pai_screen_image/off
+	name = "None"
+	icon_state = "pai-off"
+	interface_icon = "meh-blank"
+
+/datum/pai_screen_image/sad
+	name = "Sad"
+	icon_state = "pai-sad"
+	interface_icon = "sad-cry"
+
+/datum/pai_screen_image/sunglasses
+	name = "Sunglasses"
+	icon_state = "pai-sunglasses"
+	interface_icon = "sun"
+
+/datum/pai_screen_image/what
+	name = "What"
+	icon_state = "pai-what"
+	interface_icon = "frown-open"

code/modules/pai/death.dm

@@ -13,7 +13,7 @@
 	if (!QDELETED(card) && loc != card)
 		card.forceMove(drop_location())
 		card.pai = null
-		card.emotion_icon = initial(card.emotion_icon)
+		card.screen_image = initial(card.screen_image)
 		card.update_appearance()
 
 	qdel(src)

code/modules/pai/pai.dm

@@ -123,20 +123,6 @@
 		"puppy" = TRUE,
 		"spider" = TRUE,
 	)
-	/// List of all available card overlays.
-	var/static/list/possible_overlays = list(
-		"null",
-		"angry",
-		"cat",
-		"extremely-happy",
-		"face",
-		"happy",
-		"laugh",
-		"off",
-		"sad",
-		"sunglasses",
-		"what"
-	)
 
 /mob/living/silicon/pai/add_sensors() //pAIs have to buy their HUDs
 	return

code/modules/pai/software.dm

@@ -8,7 +8,7 @@
 /mob/living/silicon/pai/ui_data(mob/user)
 	var/list/data = list()
 	data["door_jack"] = hacking_cable
-	data["image"] = card.emotion_icon
+	data["screen_image_interface_icon"] = card.screen_image.interface_icon
 	data["installed"] = installed_software
 	data["ram"] = ram
 	return data
@@ -135,16 +135,16 @@
  */
 /mob/living/silicon/pai/proc/change_image()
 	var/list/possible_choices = list()
-	for(var/face_option in possible_overlays)
+	for(var/datum/pai_screen_image/screen_option as anything in subtypesof(/datum/pai_screen_image))
 		var/datum/radial_menu_choice/choice = new
-		choice.name = face_option
-		choice.image = image(icon = card.icon, icon_state = "pai-[face_option]")
-		possible_choices[face_option] += choice
+		choice.name = screen_option.name
+		choice.image = image(icon = screen_option.icon, icon_state = screen_option.icon_state)
+		possible_choices[screen_option] += choice
 	var/atom/anchor = get_atom_on_turf(src)
 	var/new_image = show_radial_menu(src, anchor, possible_choices, custom_check = CALLBACK(src, PROC_REF(check_menu), anchor), radius = 40, require_near = TRUE)
 	if(isnull(new_image))
 		return FALSE
-	card.emotion_icon = new_image
+	card.screen_image = new_image
 	card.update_appearance()
 	return TRUE