Suit Storage Unit QoL Patch (#3275)

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## About The Pull Request
- SSU 'Lock' now displays a Red Light

![image](https://github.com/user-attachments/assets/550190f0-4ee1-45df-9b3f-fe5750d0b77e)

- SSU hacked 'Super-UV' Decontamination now displays a flashing
red-yellow light to distinguish from the Locked state

![dreamseeker_dh8pZyFq19](https://github.com/user-attachments/assets/5fe4b153-a754-41d6-9b6e-ad48741d43e7)

- Feedback for failing to activate UV Decontamination due to Safeties

![image](https://github.com/user-attachments/assets/d3521063-6611-45ad-977c-ebf8cf760c80)

- Feedback for failing to activate UV Decontamination due to the SSU
being empty

![image](https://github.com/user-attachments/assets/5aca2abf-83a2-4f02-8d00-330f215fb97a)

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## Why It's Good For The Game
Some QoL for the Suit Storage Unit, including feedback and a visible
lock state
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benefit the game. If you can't justify it in words, it might not be
worth adding. -->

## Changelog

:cl:
add: Suit Storage Units now provide feedback when Decontamination fails
to activate
imageadd: Suit Storage Units now have a visible red light when Locked -
when hacked, Decontamination now has a red-yellow flashing light to
distinguish from the Locked light.
/:cl:

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code/game/machinery/suit_storage_unit.dm

@@ -231,13 +231,13 @@
 			. += "[base_icon_state]_helm"
 		if(storage)
 			. += "[base_icon_state]_storage"
-		if(uv && uv_super)
-			. += "[base_icon_state]_super"
 	if(!(machine_stat & BROKEN || machine_stat & NOPOWER))
 		if(state_open)
 			. += "[base_icon_state]_lights_open"
 		else
 			if(uv)
+				if(uv_super)
+					. += "[base_icon_state]_super"
 				. += "[base_icon_state]_lights_red"
 			else
 				. += "[base_icon_state]_lights_closed"
@@ -247,6 +247,8 @@
 				. += "[base_icon_state]_uvstrong"
 			else
 				. += "[base_icon_state]_uv"
+		else if(locked)
+			. += "[base_icon_state]_locked"
 		else
 			. += "[base_icon_state]_ready"
 
@@ -340,8 +342,10 @@
 				close_machine()
 		if ("disinfect")
 			if (occupant && safeties)
+				say("Alert: safeties triggered, occupant detected!")
 				return
 			else if (!helmet && !mask && !suit && !storage && !occupant)
+				to_chat(user, span_notice("There's nothing inside [src] to disinfect!"))
 				return
 			else
 				if (occupant)
@@ -351,6 +355,7 @@
 		if ("lock", "unlock")
 			if (!state_open)
 				locked = !locked
+				update_icon()
 		else
 			var/obj/item/item_to_dispense = vars[choice]
 			if (item_to_dispense)