Synth brain messenger notif (#3510)

## About The Pull Request

Getting a message to your brain PDA, as a synth, will now show the
detailed messenger app chat message (instead of the notification sound
only).
## Why It's Good For The Game

Convenience, so synth crew know more easily when they get a message on
their brain PDAs.
## Proof Of Testing
<details>
<summary>Screenshots/Videos</summary>
Did this with the roundstart RD PDA and a synthetic character's brain
PDA. The message with the positronic brain icon (it is fuckin small)
indicates it comes from the synth brain.


![image](https://github.com/user-attachments/assets/4e894b8e-e825-49dc-8a66-cc15a2ad3d2b)

</details>

## Changelog
🆑
qol: synth brain PDAs now have the detailed NTOS messenger notification
to their brain owners
/🆑

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

@@ -717,6 +717,14 @@
 	if(computer.loc && isliving(computer.loc))
 		receievers += computer.loc
 
+	/// BUBBER EDIT BEGINS - Synths get notified if their brain PDA is messaged
+	if(istype(computer, /obj/item/modular_computer/pda/synth))
+		var/obj/item/organ/brain/synth/brain_loc = computer.loc
+		var/mob/living/carbon/owner = brain_loc?.bodypart_owner?.owner
+		if(istype(owner))
+			receievers += owner
+	/// BUBBER EDIT ENDS
+
 	// resolving w/o nullcheck here, assume the messenger exists if a real person sent a message
 	var/datum/computer_file/program/messenger/sender_messenger = chat.recipient?.resolve()