Adds gladiuses (gladii?) (#93631)

## About The Pull Request

Adds the Gladius alongside its scabbard. Replaces undead roman
legionarries' claymores with gladii.
<img width="152" height="105" alt="image"
src="https://github.com/user-attachments/assets/fdd21960-0f73-4564-b381-7044838a0f51"
/>
<img width="194" height="165" alt="image"
src="https://github.com/user-attachments/assets/a3f602e1-9ce6-4ded-b40d-d7088da292c9"
/>
<img width="136" height="133" alt="image"
src="https://github.com/user-attachments/assets/e8105ba3-d1e5-42cb-86e5-16db6edd56f7"
/>


## Why It's Good For The Game

This started as me thinking "hmmm those guys shouldn't have longswords"
and so I gave them the gladius, the famous standard issue foot soldier
weapon for the roman army. It's better in that it's more historically
accurate, which is definitely something everyone cares about a lot.

## Changelog
🆑
add: Roman skeletons now have Roman swords.
/🆑

---------

Co-authored-by: die <96586172+grungussuss@users.noreply.github.com>

code/datums/storage/subtypes/belts.dm

@@ -294,6 +294,16 @@
 	. = ..()
 	set_holdable(/obj/item/melee/parsnip_sabre)
 
+/datum/storage/gladius_belt
+	max_slots = 1
+	do_rustle = FALSE
+	max_specific_storage = WEIGHT_CLASS_BULKY
+	click_alt_open = FALSE
+
+/datum/storage/gladius_belt/New(atom/parent, max_slots, max_specific_storage, max_total_storage, rustle_sound, remove_rustle_sound)
+	. = ..()
+	set_holdable(/obj/item/claymore/gladius)
+
 ///Plant belt
 /datum/storage/plant_belt
 	max_slots = 6