Begin, the Lag Wars Have (#21839)

<img width="700" height="848" alt="image"
src="https://github.com/user-attachments/assets/e0db50af-35db-43c7-b78e-6c1ea5ac569c"
/>

you take a tiny little two year LOA and this happens
this PR hits some large lag culprits:
- UpdateOverlays() getting spammed by human/update_icon. This was 0.85%
of server CPU time during the event. Doesn't sound like a whole lot but
it's insane. 99% of it was caused by sloppy duplicate calls of
update_icon in set_dir (as well as update icon itself!). Refactored to
stop that
- Makes Follow menu update manually, which cuts down on the 2.8 million
REF() calls it made during the event. This was ~1% of CPU time including
ui_data as well.
- Gets rid of a bunch of random runtimes and some lighting-related
harddels.
- NanoUIs now clean themselves up when their owner qdels rather than
forcing the owner to do REF(src) and close all matching UIs. saves us
~0.1% server cpu time! wowza!

code/modules/mob/abstract/ghost/ghost.dm

@@ -132,13 +132,12 @@
 	set category = "Ghost"
 	set desc = "Follow and haunt a mob."
 
-	var/datum/tgui_module/follow_menu/GM = new /datum/tgui_module/follow_menu(usr)
-	GM.ui_interact(usr)
+	GLOB.follow_menu.ui_interact(src)
 
 // This is the ghost's follow verb with an argument
 /mob/abstract/ghost/proc/ManualFollow(var/atom/movable/target)
 	if(!target)
-		return
+		return FALSE
 
 	//Stops orbit if there's any; TG doesn't do this, but if you don't it breaks the orbiting reference
 	//if you are jumping from one mob to another, hence why we're doing it here
@@ -154,6 +153,7 @@
 
 	to_chat(src, SPAN_NOTICE("Now following \the <b>[target]</b>."))
 	update_sight()
+	return TRUE
 
 /mob/abstract/ghost/proc/update_sight()
 	//if they are on a restricted level, then set the ghost vision for them.