Bitrunning hotfix 3 (#78818)

## About The Pull Request
The next round of small changes to how bitrunning works - mostly from
feedback, bug reports etc.

- The loot crate delivery spot is now a buildable machine (the
byteforge), making it replaceable in the event of a disaster
- Same for netpods and quantum consoles. These boards are now
researchable and buildable.
- New icons for the byteforge and the health monitor
- Some bug fixes around despawning avatars
- Reimplements one of the bitrunning unit tests

<details>
<summary>Pictures ⬇️</summary>

Host monitor

![hostmon](https://github.com/tgstation/tgstation/assets/42397676/dc6811bc-7ce9-4eae-a91b-96975bd13c65)

Byteforge

![dreamseeker_LewhZG8bEl](https://github.com/tgstation/tgstation/assets/42397676/3071bc5f-b2c1-47d5-8a56-b0e6c216be20)

Spawning a crate

![dreamseeker_mHGSfoeMu5](https://github.com/tgstation/tgstation/assets/42397676/d5f84e91-b9bc-4bb8-8f1c-f8931154ff6d)
</details>

## Why It's Good For The Game
Bitrunning bug fixes and personal requests
Fixes #78571 
Fixes an issue reported in discord - players stuck as gondola spawn

## Changelog
🆑
fix: Added extra checks to bitrunning domain cleanup so avatars are
deleted properly.
add: Quantum servers now look for a new machine called a byteforge to
spawn loot on- no longer on an invisible landmark. This should make the
rooms rebuildable after disasters.
add: *Most* bitrunning machinery is now researchable and buildable via
circuits in the engineering protolathe.
/🆑

code/modules/bitrunning/objects/byteforge.dm

@@ -0,0 +1,55 @@
+/obj/machinery/byteforge
+	name = "byteforge"
+
+	circuit = /obj/item/circuitboard/machine/byteforge
+	desc = "A machine used by the quantum server. Quantum code converges here, materializing decrypted assets from the virtual abyss."
+	icon = 'icons/obj/machines/bitrunning.dmi'
+	icon_state = "byteforge"
+	obj_flags = BLOCKS_CONSTRUCTION
+	/// Idle particles
+	var/mutable_appearance/byteforge_particles
+
+/obj/machinery/byteforge/Initialize(mapload)
+	. = ..()
+
+	return INITIALIZE_HINT_LATELOAD
+
+/obj/machinery/byteforge/LateInitialize()
+	. = ..()
+
+	byteforge_particles = mutable_appearance(initial(icon), "on_particles", ABOVE_MOB_LAYER)
+	setup_particles()
+
+/obj/machinery/byteforge/update_appearance(updates)
+	. = ..()
+
+	setup_particles()
+
+/// Adds the particle overlays to the byteforge
+/obj/machinery/byteforge/proc/setup_particles()
+	cut_overlays()
+
+	if(is_operational)
+		add_overlay(byteforge_particles)
+
+/// Begins spawning the crate - lights, overlays, etc
+/obj/machinery/byteforge/proc/start_to_spawn(obj/structure/closet/crate/secure/bitrunning/encrypted/cache)
+	addtimer(CALLBACK(src, PROC_REF(spawn_crate), cache), 1 SECONDS, TIMER_UNIQUE|TIMER_OVERRIDE|TIMER_STOPPABLE)
+
+	var/mutable_appearance/lighting = mutable_appearance(initial(icon), "on_overlay")
+	flick_overlay_view(lighting, 1 SECONDS)
+
+	set_light(l_range = 2, l_power = 1.5, l_color = LIGHT_COLOR_BABY_BLUE, l_on = TRUE)
+
+/// Sparks, moves the crate to the location
+/obj/machinery/byteforge/proc/spawn_crate(obj/structure/closet/crate/secure/bitrunning/encrypted/cache)
+	if(QDELETED(cache))
+		return
+
+	playsound(src, 'sound/magic/blink.ogg', 50, TRUE)
+	var/datum/effect_system/spark_spread/quantum/sparks = new()
+	sparks.set_up(5, 1, loc)
+	sparks.start()
+
+	cache.forceMove(loc)
+	set_light(l_on = FALSE)

code/modules/bitrunning/objects/host_monitor.dm

@@ -2,10 +2,10 @@
 	name = "host monitor"
 
 	custom_materials = list(/datum/material/iron = SMALL_MATERIAL_AMOUNT * 2)
-	desc = "A complex medical device that, when attached to an avatar's data stream, can detect the user of their host's health."
+	desc = "A complex electronic that will analyze the connection health between host and avatar."
 	flags_1 = CONDUCT_1
 	icon = 'icons/obj/device.dmi'
-	icon_state = "gps-b"
+	icon_state = "host_monitor"
 	inhand_icon_state = "electronic"
 	item_flags = NOBLUDGEON
 	lefthand_file = 'icons/mob/inhands/items/devices_lefthand.dmi'

code/modules/bitrunning/objects/landmarks.dm

@@ -44,11 +44,6 @@
 
 	qdel(src)
 
-/// Where the crates get ported to station
-/obj/effect/landmark/bitrunning/station_reward_spawn
-	name = "Bitrunning rewards spawn"
-	icon_state = "station"
-
 /// Where the exit hololadder spawns
 /obj/effect/landmark/bitrunning/hololadder_spawn
 	name = "Bitrunning hololadder spawn"

code/modules/bitrunning/objects/netpod.dm

@@ -189,7 +189,7 @@
 	return TRUE
 
 /obj/machinery/netpod/ui_interact(mob/user, datum/tgui/ui)
-	if(!is_operational)
+	if(!is_operational || occupant)
 		return
 
 	ui = SStgui.try_update_ui(user, src, ui)
@@ -242,20 +242,12 @@
 	to_chat(player, span_notice("The machine disconnects itself and begins to drain."))
 	open_machine()
 
-/**
- * ### Disconnect occupant
- * If this goes smoothly, should reconnect a receiving mind to the occupant's body
- *
- * This is the second stage of the process -  if you want to disconn avatars start at the mind first
- */
+/// Handles occupant post-disconnection effects like damage, sounds, etc
 /obj/machinery/netpod/proc/disconnect_occupant(forced = FALSE)
-	var/mob/living/mob_occupant = occupant
-	if(isnull(occupant) || !isliving(occupant))
-		return
-
 	connected = FALSE
 
-	if(mob_occupant.stat == DEAD)
+	var/mob/living/mob_occupant = occupant
+	if(isnull(occupant) || !isliving(occupant) || mob_occupant.stat == DEAD)
 		open_machine()
 		return
 
@@ -347,8 +339,9 @@
 		return
 
 	server_ref = WEAKREF(server)
-	RegisterSignal(server, COMSIG_BITRUNNER_SERVER_UPGRADED, PROC_REF(on_server_upgraded), override = TRUE)
-	RegisterSignal(server, COMSIG_BITRUNNER_DOMAIN_COMPLETE, PROC_REF(on_domain_complete), override = TRUE)
+	RegisterSignal(server, COMSIG_BITRUNNER_SERVER_UPGRADED, PROC_REF(on_server_upgraded))
+	RegisterSignal(server, COMSIG_BITRUNNER_DOMAIN_COMPLETE, PROC_REF(on_domain_complete))
+	RegisterSignal(server, COMSIG_BITRUNNER_DOMAIN_SCRUBBED, PROC_REF(on_domain_scrubbed))
 
 	return server
 
@@ -395,6 +388,7 @@
 
 	account.bitrunning_points += reward_points * 100
 
+/// User inspects the machine
 /obj/machinery/netpod/proc/on_examine(datum/source, mob/examiner, list/examine_text)
 	SIGNAL_HANDLER
 
@@ -409,7 +403,15 @@
 	examine_text += span_notice("It is currently occupied by [occupant].")
 	examine_text += span_notice("It can be pried open with a crowbar, but its safety mechanisms will alert the occupant.")
 
+/// The domain has been fully purged, so we should double check our avatar is deleted
+/obj/machinery/netpod/proc/on_domain_scrubbed(datum/source)
+	SIGNAL_HANDLER
 
+	var/mob/living/current_avatar = avatar_ref?.resolve()
+	if(isnull(current_avatar))
+		return
+
+	QDEL_NULL(current_avatar)
 
 /// When the server is upgraded, drops brain damage a little
 /obj/machinery/netpod/proc/on_server_upgraded(datum/source, servo_rating)