Build Mode Hard Del Fix (#22293)

<img width="376" height="128" alt="image"
src="https://github.com/user-attachments/assets/346bda21-2a87-424b-8072-806bfdaa81d2"
/>

Fixes this hard del, which was triggered by admin commands.

code/modules/admin/buildmode/advanced.dm

@@ -3,6 +3,10 @@
 	icon_state = "buildmode2"
 	var/build_type
 
+/datum/build_mode/advanced/Destroy()
+	build_type = null
+	. = ..()
+
 /datum/build_mode/advanced/Help()
 	to_chat(user, SPAN_NOTICE("***********************************************************"))
 	to_chat(user, SPAN_NOTICE("Left Click                       = Create objects"))

code/modules/admin/buildmode/buildmode.dm

@@ -14,6 +14,7 @@
 
 /datum/build_mode/Destroy()
 	host = null
+	user = null
 	. = ..()
 
 /datum/build_mode/proc/OnClick(var/atom/A, var/list/parameters)

code/modules/admin/buildmode/ladders.dm

@@ -4,6 +4,11 @@
 	var/turf/ladder_upper
 	var/turf/ladder_lower
 
+/datum/build_mode/ladders/Destroy()
+	ladder_upper = null
+	ladder_lower = null
+	. = ..()
+
 /datum/build_mode/ladders/Help()
 	to_chat(user, SPAN_NOTICE("***********************************************************"))
 	to_chat(user, SPAN_NOTICE("Left Click on Turf   = Set as upper ladder loc"))

code/modules/admin/buildmode/room_builder.dm

@@ -8,6 +8,11 @@
 	var/floor_type = /turf/simulated/floor/plating
 	var/wall_type = /turf/simulated/wall
 
+/datum/build_mode/room_builder/Destroy()
+	coordinate_A = null
+	coordinate_B = null
+	. = ..()
+
 /datum/build_mode/room_builder/Help()
 	to_chat(user, SPAN_NOTICE("***********************************************************"))
 	to_chat(user, SPAN_NOTICE("Left Click on Turf               = Select as point A"))