Adds Holodisks to Loadout Options (#89958)

## About The Pull Request

This adds holodisks to the loadout options pool.

## Why It's Good For The Game

I have _never_ seen this item used in game. Like many other cool items
it has been banished to the toy vendor, but unlike the hoverboard it is
not just a vanity item to show that you have lots of money. By taking it
out into the light alongside dice and trading cards I hope it will be
used more often, because holograms are cool. From what I understand the
item does not conflict with the loadout guidelines, it's an in-pocket
item so it does not conflict with silhouette, it is not distracting for
the same reason, most jobs can purchase it roundstart (I believe only
one or two jobs lack the roundstart credits to afford it), and because
it is a hologram it cannot provide much mechanical benefit outside of
roleplay. Ideally these would be used to record things like this:


![Hologram](https://github.com/user-attachments/assets/4fb9c464-bdaa-4c2f-a01e-ddadf434761d)

That would be a cool thing to find on a dead person.

## Changelog

🆑
add: Added Holodisks to loadout options
/🆑

code/modules/loadout/categories/pocket.dm

@@ -253,6 +253,10 @@
 	name = "Poster (Pinup)"
 	item_path = /obj/item/poster/random_contraband/pinup
 
+/datum/loadout_item/pocket_items/holodisk
+	name = "Holodisk"
+	item_path = /obj/item/disk/holodisk
+
 // The wallet loadout item is special, and puts the player's ID and other small items into it on initialize (fancy!)
 /datum/loadout_item/pocket_items/wallet
 	name = "Wallet"