Stops HFRs (and other INDESTRUCTIBLE machinery) from being able to be blown up if an explosion's epicenter is on the tile (#62164)

* Stops HFRs from being able to be blown up if an explosion's epicenter is on the tile

* Stops stationloving objects from being able to be teleported to HFR core

* Automatically add PREVENT_CONTENTS_EXPLOSION_1 to all INDESTRUCTIBLE machinery

* Document reason for PREVENT_CONTENTS_EXPLOSION_1 flag being needed

code/modules/atmospherics/machinery/components/fusion/hfr_core.dm

@@ -171,6 +171,15 @@
 	radio.listening = 0
 	radio.recalculateChannels()
 	investigate_log("has been created.", INVESTIGATE_HYPERTORUS)
+	
+	RegisterSignal(src.loc, COMSIG_ATOM_ENTERED, .proc/on_entered)
+
+	for(var/atom/movable/movable_object in src.loc)
+		SEND_SIGNAL(movable_object, COMSIG_MOVABLE_SECLUDED_LOCATION)
+
+/obj/machinery/atmospherics/components/unary/hypertorus/core/proc/on_entered(datum/source, atom/movable/arrived, atom/old_loc, list/atom/old_locs)
+	SIGNAL_HANDLER
+	SEND_SIGNAL(arrived, COMSIG_MOVABLE_SECLUDED_LOCATION) // to prevent stationloving items (eg. nuke disk) being teleported onto core
 
 /obj/machinery/atmospherics/components/unary/hypertorus/core/Destroy()
 	unregister_signals(TRUE)

code/modules/atmospherics/machinery/components/fusion/hfr_parts.dm

@@ -11,6 +11,7 @@
 	anchored = TRUE
 	density = TRUE
 	resistance_flags = INDESTRUCTIBLE | LAVA_PROOF | FIRE_PROOF | UNACIDABLE | ACID_PROOF | FREEZE_PROOF
+	flags_1 = PREVENT_CONTENTS_EXPLOSION_1
 	layer = OBJ_LAYER
 	pipe_flags = PIPING_ONE_PER_TURF | PIPING_DEFAULT_LAYER_ONLY
 	circuit = /obj/item/circuitboard/machine/thermomachine
@@ -128,6 +129,7 @@
 	anchored = TRUE
 	density = TRUE
 	resistance_flags = INDESTRUCTIBLE | LAVA_PROOF | FIRE_PROOF | UNACIDABLE | ACID_PROOF | FREEZE_PROOF
+	flags_1 = PREVENT_CONTENTS_EXPLOSION_1
 	power_channel = AREA_USAGE_ENVIRON
 	var/active = FALSE
 	var/icon_state_open