NT Frontier lets you refund researched nodes (#94074)

## About The Pull Request

If you research a node you can still buy it from NT Frontier, and when
you do it refunds the research points you spent. It's like how
experi-scanners work.

Also cytology gives you an 80 point discount instead of a 120 point
discount. This doesn't change anything because it only costs 80 points
and NT Frontier boosts can't make costs go negative.

## Why It's Good For The Game

Right now it's most efficient to delay research until ordnance gets
finished and then grab all the free stuff, and any head of staff
researching stuff for their own deparment or robo that wants to make
cool mechs can fuck things up. That's not great, because it's
unrealistic to expect everyone to be coordinated and delaying research
never gets tried in practice.

Also, doing ordnance after the round has been going on for a while is
way less effective because all of the nodes you would've discounted were
already researched.

## Changelog
🆑
balance: NT Frontier can purchase and refund researched techweb nodes.
/🆑

---------

Co-authored-by: Fghj240 <fakeemail@notrealemail.com>

code/modules/modular_computers/file_system/programs/frontier.dm

@@ -155,7 +155,8 @@
 					else
 						data["relations"][partner.type] = "Undefined"
 				data["purchaseableBoosts"][partner.type] = list()
-				for(var/node_id in linked_techweb.get_available_nodes())
+				var/displayable_nodes = linked_techweb.get_available_nodes() + linked_techweb.get_researched_nodes()
+				for(var/node_id in displayable_nodes)
 					// Not from our partner
 					if(!(node_id in partner.boostable_nodes))
 						continue
@@ -218,8 +219,9 @@
 			var/datum/scientific_partner/partner = locate(text2path(params["boost_seller"])) in SSresearch.scientific_partners
 			var/datum/techweb_node/node = SSresearch.techweb_node_by_id(params["purchased_boost"])
 			if(partner && node)
-				if(partner.purchase_boost(linked_techweb, node))
-					computer.say("Purchase successful.")
+				var/possible_boost = partner.purchase_boost(linked_techweb, node)
+				if(possible_boost)
+					computer.say("Purchase successful[possible_boost == SCIPAPER_ALREADY_BOUGHT ? ", refunding [partner.boostable_nodes[params["purchased_boost"]]] points" : ""].")
 					playsound(computer, 'sound/machines/ping.ogg', 25)
 					return TRUE
 			playsound(computer, 'sound/machines/terminal/terminal_error.ogg', 25)