Ports two of my recent /tg/ PRs (#3896)

* PDA ringtones now show a balloon alert (#87278)

This makes it so receiving a PDA message will give the holder a balloon
alert with their ringtone.

PDA messages are often ignored due to not being noticed, as many players
are more often focused on the main game screen (which runechat has
somewhat normalized) than the chat window. This makes things more
obvious that there's a PDA message.

:cl:
add: PDA ringtones now show a balloon alert to the PDA holder.
/:cl:

* Master-overlayed screen alerts (i.e aura healing) now use appearance cloning instead of directly overlaying the master (#87281)

## About The Pull Request

This reworks the `/mob/proc/throw_alert(new_master = ...)` to use
appearance cloning instead of just directly adding the master atom as an
overlay.

There's several advantages to this:
- We don't have to change anything about the original target at all
- Setting the plane/layer, adding the overlay, then resetting it to
before (as it does without this PR), feels like an awful hack ngl.
- We can ensure the target is always facing south, and has no pixel
x/y/z shift.

<details>
<summary><h3>Proof of testing / screenshots</h3></summary>

I had the healing rod holder standing on a table when the alert was
added, to ensure that the pixel_x/y/z reset worked.

![2024-10-17 (1729221218) ~
dreamseeker](https://github.com/user-attachments/assets/664abbef-d543-4d13-99ec-3264e05edfd8)
![2024-10-17 (1729221245) ~
dreamseeker](https://github.com/user-attachments/assets/6073dcd4-75e0-404a-bea1-6bea5fbd7591)

</details>

## Why It's Good For The Game

Ensures the aura healing alerts and such always look consistent - no
pixel offsets, always facing south, with more reliable code.

## Changelog
:cl:
refactor: Refactored how some screen alerts, such as aura healing, show
atom overlays.
/:cl:

code/_onclick/hud/alert.dm

@@ -47,13 +47,15 @@
 	thealert.owner = src
 
 	if(new_master)
-		var/old_layer = new_master.layer
-		var/old_plane = new_master.plane
-		new_master.layer = FLOAT_LAYER
-		new_master.plane = FLOAT_PLANE
-		thealert.add_overlay(new_master)
-		new_master.layer = old_layer
-		new_master.plane = old_plane
+		var/mutable_appearance/master_appearance = new(new_master)
+		master_appearance.appearance_flags = KEEP_TOGETHER
+		master_appearance.layer = FLOAT_LAYER
+		master_appearance.plane = FLOAT_PLANE
+		master_appearance.dir = SOUTH
+		master_appearance.pixel_x = new_master.base_pixel_x
+		master_appearance.pixel_y = new_master.base_pixel_y
+		master_appearance.pixel_z = 0 /* new_master.base_pixel_z */
+		thealert.add_overlay(master_appearance)
 		thealert.icon_state = "template" // We'll set the icon to the client's ui pref in reorganize_alerts()
 		thealert.master = new_master
 	else

code/modules/modular_computers/computers/item/computer.dm

@@ -503,12 +503,15 @@
 	playsound(src, sound, 50, TRUE)
 	loc.visible_message(span_notice("[icon2html(src)] [span_notice("The [src] displays a [origin.filedesc] notification: [alerttext]")]"))
 
-/obj/item/modular_computer/proc/ring(ringtone) // bring bring
+/obj/item/modular_computer/proc/ring(ringtone, list/balloon_alertees) // bring bring
 	if(HAS_TRAIT(SSstation, STATION_TRAIT_PDA_GLITCHED))
 		playsound(src, pick('sound/machines/twobeep_voice1.ogg', 'sound/machines/twobeep_voice2.ogg'), 50, TRUE)
 	else
 		playsound(src, 'sound/machines/twobeep_high.ogg', 50, TRUE)
-	audible_message("*[ringtone]*")
+	ringtone = "*[ringtone]*"
+	audible_message(ringtone)
+	for(var/mob/living/alertee in balloon_alertees)
+		alertee.balloon_alert(alertee, ringtone)
 
 /obj/item/modular_computer/proc/send_sound()
 	playsound(src, 'sound/machines/terminal_success.ogg', 15, TRUE)

code/modules/modular_computers/file_system/programs/messenger/messenger_program.dm

@@ -686,7 +686,7 @@
 		to_chat(receiver_mob, span_infoplain("[icon2html(computer, receiver_mob)] <b>PDA message from [sender_title], </b>\"[inbound_message]\"[photo_message] [reply]"))
 
 	if (alert_able && should_ring)
-		computer.ring(ringtone)
+		computer.ring(ringtone, list(receiver_mob))
 
 	SStgui.update_uis(computer)
 	update_pictures_for_all()